[MM-37557] Move error out of client4 response (#18101)

* Return an error seperately from Response

* Remove BuildErrorResponse

* Drop Response.Error from model/client4.go

* Migrate require.Nil checks

* Migrate require.NotNil checks

* More manual fixes

* Move error check out of CheckOKStatus and CheckCreatedStatus

* Move error check out of CheckForbiddenStatus

* Move error check out of CheckUnauthorizedStatus

* Move error check out of CheckNotFoundStatus

* Move error check out of CheckBadRequestStatus

* Move error check out of CheckNotImplementedStatus and CheckRequestEntityTooLargeStatus

* Move error check out of CheckInternalErrorStatus

* Move error check out of CheckServiceUnavailableStatus

* Remove error check from checkHTTPStatus

* Remove remaining references to Response.Error

* Check previously unchecked errors

* Manually fix compile and linter errors

* Return error in CreateWebSocket methods

* Return error instead of *AppError in DoApi methods

* Manually fix bad replacments

* Conistently return Response and error

* Use err instead of seperate bool return value to indicate success

* Reduce ussage of model.AppError in web/oauth_test.go

* Remove client4.Must

* Check error in buf.ReadFrom

* Fix failing tests

api4/preference_test.go

@@ -17,7 +17,7 @@ import (
 func TestGetPreferences(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+	client := th.Client
 
 	// recreate basic user (cached has no default preferences)
 	th.BasicUser = th.CreateUser()
@@ -44,10 +44,10 @@ func TestGetPreferences(t *testing.T) {
 		},
 	}
 
-	Client.UpdatePreferences(user1.Id, &preferences1)
+	client.UpdatePreferences(user1.Id, &preferences1)
 
-	prefs, resp := Client.GetPreferences(user1.Id)
-	CheckNoError(t, resp)
+	prefs, _, err := client.GetPreferences(user1.Id)
+	require.NoError(t, err)
 
 	// 5 because we have 2 initial preferences tutorial_step and recommended_next_steps added when creating a new user
 	require.Equal(t, len(prefs), 5, "received the wrong number of preferences")
@@ -60,23 +60,25 @@ func TestGetPreferences(t *testing.T) {
 	th.BasicUser2 = th.CreateUser()
 	th.LoginBasic2()
 
-	prefs, resp = Client.GetPreferences(th.BasicUser2.Id)
-	CheckNoError(t, resp)
+	prefs, _, err = client.GetPreferences(th.BasicUser2.Id)
+	require.NoError(t, err)
 
 	require.Greater(t, len(prefs), 0, "received the wrong number of preferences")
 
-	_, resp = Client.GetPreferences(th.BasicUser.Id)
+	_, resp, err := client.GetPreferences(th.BasicUser.Id)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
-	Client.Logout()
-	_, resp = Client.GetPreferences(th.BasicUser2.Id)
+	client.Logout()
+	_, resp, err = client.GetPreferences(th.BasicUser2.Id)
+	require.Error(t, err)
 	CheckUnauthorizedStatus(t, resp)
 }
 
 func TestGetPreferencesByCategory(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+	client := th.Client
 
 	th.LoginBasic()
 	user1 := th.BasicUser
@@ -100,38 +102,43 @@ func TestGetPreferencesByCategory(t *testing.T) {
 		},
 	}
 
-	Client.UpdatePreferences(user1.Id, &preferences1)
+	client.UpdatePreferences(user1.Id, &preferences1)
 
-	prefs, resp := Client.GetPreferencesByCategory(user1.Id, category)
-	CheckNoError(t, resp)
+	prefs, _, err := client.GetPreferencesByCategory(user1.Id, category)
+	require.NoError(t, err)
 
 	require.Equal(t, len(prefs), 2, "received the wrong number of preferences")
 
-	_, resp = Client.GetPreferencesByCategory(user1.Id, "junk")
+	_, resp, err := client.GetPreferencesByCategory(user1.Id, "junk")
+	require.Error(t, err)
 	CheckNotFoundStatus(t, resp)
 
 	th.LoginBasic2()
 
-	_, resp = Client.GetPreferencesByCategory(th.BasicUser2.Id, category)
+	_, resp, err = client.GetPreferencesByCategory(th.BasicUser2.Id, category)
+	require.Error(t, err)
 	CheckNotFoundStatus(t, resp)
 
-	_, resp = Client.GetPreferencesByCategory(user1.Id, category)
+	_, resp, err = client.GetPreferencesByCategory(user1.Id, category)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
-	prefs, resp = Client.GetPreferencesByCategory(th.BasicUser2.Id, "junk")
+	prefs, resp, err = client.GetPreferencesByCategory(th.BasicUser2.Id, "junk")
+	require.Error(t, err)
 	CheckNotFoundStatus(t, resp)
 
 	require.Equal(t, len(prefs), 0, "received the wrong number of preferences")
 
-	Client.Logout()
-	_, resp = Client.GetPreferencesByCategory(th.BasicUser2.Id, category)
+	client.Logout()
+	_, resp, err = client.GetPreferencesByCategory(th.BasicUser2.Id, category)
+	require.Error(t, err)
 	CheckUnauthorizedStatus(t, resp)
 }
 
 func TestGetPreferenceByCategoryAndName(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+	client := th.Client
 
 	th.LoginBasic()
 	user := th.BasicUser
@@ -153,32 +160,36 @@ func TestGetPreferenceByCategoryAndName(t *testing.T) {
 		},
 	}
 
-	Client.UpdatePreferences(user.Id, &preferences)
+	client.UpdatePreferences(user.Id, &preferences)
 
-	pref, resp := Client.GetPreferenceByCategoryAndName(user.Id, model.PreferenceCategoryDirectChannelShow, name)
-	CheckNoError(t, resp)
+	pref, _, err := client.GetPreferenceByCategoryAndName(user.Id, model.PreferenceCategoryDirectChannelShow, name)
+	require.NoError(t, err)
 
 	require.Equal(t, preferences[0].UserId, pref.UserId, "UserId preference not saved")
 	require.Equal(t, preferences[0].Category, pref.Category, "Category preference not saved")
 	require.Equal(t, preferences[0].Name, pref.Name, "Name preference not saved")
 
 	preferences[0].Value = model.NewId()
-	Client.UpdatePreferences(user.Id, &preferences)
+	client.UpdatePreferences(user.Id, &preferences)
 
-	_, resp = Client.GetPreferenceByCategoryAndName(user.Id, "junk", preferences[0].Name)
+	_, resp, err := client.GetPreferenceByCategoryAndName(user.Id, "junk", preferences[0].Name)
+	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
 
-	_, resp = Client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, "junk")
+	_, resp, err = client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, "junk")
+	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
 
-	_, resp = Client.GetPreferenceByCategoryAndName(th.BasicUser2.Id, preferences[0].Category, "junk")
+	_, resp, err = client.GetPreferenceByCategoryAndName(th.BasicUser2.Id, preferences[0].Category, "junk")
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
-	_, resp = Client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, preferences[0].Name)
-	CheckNoError(t, resp)
+	_, _, err = client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, preferences[0].Name)
+	require.NoError(t, err)
 
-	Client.Logout()
-	_, resp = Client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, preferences[0].Name)
+	client.Logout()
+	_, resp, err = client.GetPreferenceByCategoryAndName(user.Id, preferences[0].Category, preferences[0].Name)
+	require.Error(t, err)
 	CheckUnauthorizedStatus(t, resp)
 
 }
@@ -186,7 +197,7 @@ func TestGetPreferenceByCategoryAndName(t *testing.T) {
 func TestUpdatePreferences(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+	client := th.Client
 
 	th.LoginBasic()
 	user1 := th.BasicUser
@@ -210,8 +221,8 @@ func TestUpdatePreferences(t *testing.T) {
 		},
 	}
 
-	_, resp := Client.UpdatePreferences(user1.Id, &preferences1)
-	CheckNoError(t, resp)
+	_, err := client.UpdatePreferences(user1.Id, &preferences1)
+	require.NoError(t, err)
 
 	preferences := model.Preferences{
 		{
@@ -221,7 +232,8 @@ func TestUpdatePreferences(t *testing.T) {
 		},
 	}
 
-	_, resp = Client.UpdatePreferences(user1.Id, &preferences)
+	resp, err := client.UpdatePreferences(user1.Id, &preferences)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
 	preferences = model.Preferences{
@@ -231,14 +243,17 @@ func TestUpdatePreferences(t *testing.T) {
 		},
 	}
 
-	_, resp = Client.UpdatePreferences(user1.Id, &preferences)
+	resp, err = client.UpdatePreferences(user1.Id, &preferences)
+	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
 
-	_, resp = Client.UpdatePreferences(th.BasicUser2.Id, &preferences)
+	resp, err = client.UpdatePreferences(th.BasicUser2.Id, &preferences)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
-	Client.Logout()
-	_, resp = Client.UpdatePreferences(user1.Id, &preferences1)
+	client.Logout()
+	resp, err = client.UpdatePreferences(user1.Id, &preferences1)
+	require.Error(t, err)
 	CheckUnauthorizedStatus(t, resp)
 }
 
@@ -247,7 +262,7 @@ func TestUpdatePreferencesWebsocket(t *testing.T) {
 	defer th.TearDown()
 
 	WebSocketClient, err := th.CreateWebSocketClient()
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	WebSocketClient.Listen()
 	time.Sleep(300 * time.Millisecond)
@@ -268,8 +283,8 @@ func TestUpdatePreferencesWebsocket(t *testing.T) {
 		},
 	}
 
-	_, resp := th.Client.UpdatePreferences(userId, preferences)
-	CheckNoError(t, resp)
+	_, err = th.Client.UpdatePreferences(userId, preferences)
+	require.NoError(t, err)
 
 	timeout := time.After(300 * time.Millisecond)
 
@@ -308,22 +323,22 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 		team1 := th.CreateTeam()
 		th.LinkUserToTeam(user, team1)
 
-		_, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		_, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 
 		channel := th.CreateChannelWithClientAndTeam(th.Client, model.ChannelTypeOpen, team1.Id)
 		th.AddUserToChannel(user, channel)
 
 		// Confirm that the sidebar is populated correctly to begin with
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
 		// Favorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -331,18 +346,18 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel was added to the Favorites
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		assert.NotContains(t, categories.Categories[1].Channels, channel.Id)
 
 		// And unfavorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -350,11 +365,11 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "false",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should've been removed from the Favorites
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
@@ -376,7 +391,7 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 		dmChannel := th.CreateDmChannel(user2)
 
 		// Favorite the channel
-		_, resp := th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err := th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -384,25 +399,25 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel was added to the Favorites on all teams
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.NotContains(t, categories.Categories[2].Channels, dmChannel.Id)
 
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.NotContains(t, categories.Categories[2].Channels, dmChannel.Id)
 
 		// And unfavorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -410,18 +425,18 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "false",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should've been removed from the Favorites on all teams
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.Contains(t, categories.Categories[2].Channels, dmChannel.Id)
 
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
@@ -442,32 +457,32 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 		th.LinkUserToTeam(user, team1)
 		th.LinkUserToTeam(user2, team1)
 
-		_, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
-		_, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		_, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
+		_, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 
 		channel := th.CreateChannelWithClientAndTeam(th.Client, model.ChannelTypeOpen, team1.Id)
 		th.AddUserToChannel(user, channel)
 		th.AddUserToChannel(user2, channel)
 
 		// Confirm that the sidebar is populated correctly to begin with
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
 		// Favorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -475,18 +490,18 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel was not added to Favorites for the second user
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		assert.Contains(t, categories.Categories[1].Channels, channel.Id)
 
 		// Favorite the channel for the second user
-		_, resp = client2.UpdatePreferences(user2.Id, &model.Preferences{
+		_, err = client2.UpdatePreferences(user2.Id, &model.Preferences{
 			{
 				UserId:   user2.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -494,18 +509,18 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel is now in the Favorites for the second user
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		assert.NotContains(t, categories.Categories[1].Channels, channel.Id)
 
 		// And unfavorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -513,11 +528,11 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 				Value:    "false",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should still be in the second user's favorites
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
@@ -528,11 +543,11 @@ func TestUpdateSidebarPreferences(t *testing.T) {
 func TestDeletePreferences(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+	client := th.Client
 
 	th.LoginBasic()
 
-	prefs, _ := Client.GetPreferences(th.BasicUser.Id)
+	prefs, _, _ := client.GetPreferences(th.BasicUser.Id)
 	originalCount := len(prefs)
 
 	// save 10 preferences
@@ -546,27 +561,30 @@ func TestDeletePreferences(t *testing.T) {
 		preferences = append(preferences, preference)
 	}
 
-	Client.UpdatePreferences(th.BasicUser.Id, &preferences)
+	client.UpdatePreferences(th.BasicUser.Id, &preferences)
 
 	// delete 10 preferences
 	th.LoginBasic2()
 
-	_, resp := Client.DeletePreferences(th.BasicUser2.Id, &preferences)
+	resp, err := client.DeletePreferences(th.BasicUser2.Id, &preferences)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
 	th.LoginBasic()
 
-	_, resp = Client.DeletePreferences(th.BasicUser.Id, &preferences)
-	CheckNoError(t, resp)
+	_, err = client.DeletePreferences(th.BasicUser.Id, &preferences)
+	require.NoError(t, err)
 
-	_, resp = Client.DeletePreferences(th.BasicUser2.Id, &preferences)
+	resp, err = client.DeletePreferences(th.BasicUser2.Id, &preferences)
+	require.Error(t, err)
 	CheckForbiddenStatus(t, resp)
 
-	prefs, _ = Client.GetPreferences(th.BasicUser.Id)
+	prefs, _, _ = client.GetPreferences(th.BasicUser.Id)
 	require.Len(t, prefs, originalCount, "should've deleted preferences")
 
-	Client.Logout()
-	_, resp = Client.DeletePreferences(th.BasicUser.Id, &preferences)
+	client.Logout()
+	resp, err = client.DeletePreferences(th.BasicUser.Id, &preferences)
+	require.Error(t, err)
 	CheckUnauthorizedStatus(t, resp)
 }
 
@@ -587,18 +605,18 @@ func TestDeletePreferencesWebsocket(t *testing.T) {
 			Name:     model.NewId(),
 		},
 	}
-	_, resp := th.Client.UpdatePreferences(userId, preferences)
-	CheckNoError(t, resp)
+	_, err := th.Client.UpdatePreferences(userId, preferences)
+	require.NoError(t, err)
 
 	WebSocketClient, err := th.CreateWebSocketClient()
-	require.Nil(t, err)
+	require.NoError(t, err)
 
 	WebSocketClient.Listen()
 	wsResp := <-WebSocketClient.ResponseChannel
 	require.Equal(t, model.StatusOk, wsResp.Status, "should have responded OK to authentication challenge")
 
-	_, resp = th.Client.DeletePreferences(userId, preferences)
-	CheckNoError(t, resp)
+	_, err = th.Client.DeletePreferences(userId, preferences)
+	require.NoError(t, err)
 
 	timeout := time.After(30000 * time.Millisecond)
 
@@ -637,22 +655,22 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 		team1 := th.CreateTeam()
 		th.LinkUserToTeam(user, team1)
 
-		_, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		_, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 
 		channel := th.CreateChannelWithClientAndTeam(th.Client, model.ChannelTypeOpen, team1.Id)
 		th.AddUserToChannel(user, channel)
 
 		// Confirm that the sidebar is populated correctly to begin with
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
 		// Favorite the channel
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -660,29 +678,28 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
-
+		require.NoError(t, err)
 		// Confirm that the channel was added to the Favorites
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		assert.NotContains(t, categories.Categories[1].Channels, channel.Id)
 
 		// And unfavorite the channel by deleting the preference
-		_, resp = th.Client.DeletePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.DeletePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
 				Name:     channel.Id,
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should've been removed from the Favorites
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
@@ -704,7 +721,7 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 		dmChannel := th.CreateDmChannel(user2)
 
 		// Favorite the channel
-		_, resp := th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err := th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -712,43 +729,43 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel was added to the Favorites on all teams
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.NotContains(t, categories.Categories[2].Channels, dmChannel.Id)
 
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.NotContains(t, categories.Categories[2].Channels, dmChannel.Id)
 
 		// And unfavorite the channel by deleting the preference
-		_, resp = th.Client.DeletePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.DeletePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
 				Name:     dmChannel.Id,
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should've been removed from the Favorites on all teams
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
 		assert.Contains(t, categories.Categories[2].Channels, dmChannel.Id)
 
-		categories, resp = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team2.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, dmChannel.Id)
 		require.Equal(t, model.SidebarCategoryDirectMessages, categories.Categories[2].Type)
@@ -769,32 +786,32 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 		th.LinkUserToTeam(user, team1)
 		th.LinkUserToTeam(user2, team1)
 
-		_, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
-		_, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		_, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
+		_, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 
 		channel := th.CreateChannelWithClientAndTeam(th.Client, model.ChannelTypeOpen, team1.Id)
 		th.AddUserToChannel(user, channel)
 		th.AddUserToChannel(user2, channel)
 
 		// Confirm that the sidebar is populated correctly to begin with
-		categories, resp := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err := th.Client.GetSidebarCategoriesForTeamForUser(user.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		require.NotContains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		require.Contains(t, categories.Categories[1].Channels, channel.Id)
 
 		// Favorite the channel for both users
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -802,9 +819,9 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
-		_, resp = client2.UpdatePreferences(user2.Id, &model.Preferences{
+		_, err = client2.UpdatePreferences(user2.Id, &model.Preferences{
 			{
 				UserId:   user2.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -812,18 +829,18 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 				Value:    "true",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// Confirm that the channel is in the Favorites for the second user
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)
 		assert.NotContains(t, categories.Categories[1].Channels, channel.Id)
 
 		// And unfavorite the channel for the first user by deleting the preference
-		_, resp = th.Client.UpdatePreferences(user.Id, &model.Preferences{
+		_, err = th.Client.UpdatePreferences(user.Id, &model.Preferences{
 			{
 				UserId:   user.Id,
 				Category: model.PreferenceCategoryFavoriteChannel,
@@ -831,11 +848,11 @@ func TestDeleteSidebarPreferences(t *testing.T) {
 				Value:    "false",
 			},
 		})
-		require.Nil(t, resp.Error)
+		require.NoError(t, err)
 
 		// The channel should still be in the second user's favorites
-		categories, resp = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
-		require.Nil(t, resp.Error)
+		categories, _, err = client2.GetSidebarCategoriesForTeamForUser(user2.Id, team1.Id, "")
+		require.NoError(t, err)
 		require.Equal(t, model.SidebarCategoryFavorites, categories.Categories[0].Type)
 		assert.Contains(t, categories.Categories[0].Channels, channel.Id)
 		require.Equal(t, model.SidebarCategoryChannels, categories.Categories[1].Type)