[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

app/plugin_api_test.go

@@ -1709,8 +1709,8 @@ func TestPluginHTTPUpgradeWebSocket(t *testing.T) {
 	require.NotEmpty(t, pluginID)
 
 	reqURL := fmt.Sprintf("ws://localhost:%d/plugins/%s", th.Server.ListenAddr.Port, pluginID)
-	wsc, appErr := model.NewWebSocketClient(reqURL, "")
-	require.Nil(t, appErr)
+	wsc, err := model.NewWebSocketClient(reqURL, "")
+	require.NoError(t, err)
 	require.NotNil(t, wsc)
 
 	wsc.Listen()

app/slashcommands/auto_environment.go

@@ -77,14 +77,14 @@ func CreateTestEnvironmentInTeam(a *app.App, c *request.Context, client *model.C
 	// Have every user join every channel
 	for _, user := range users {
 		for _, channel := range channels {
-			_, resp := client.LoginById(user.Id, UserPassword)
-			if resp.Error != nil {
-				return TeamEnvironment{}, resp.Error
+			_, _, err := client.LoginById(user.Id, UserPassword)
+			if err != nil {
+				return TeamEnvironment{}, err
 			}
 
-			_, resp = client.AddChannelMember(channel.Id, user.Id)
-			if resp.Error != nil {
-				return TeamEnvironment{}, resp.Error
+			_, _, err = client.AddChannelMember(channel.Id, user.Id)
+			if err != nil {
+				return TeamEnvironment{}, err
 			}
 		}
 	}
@@ -93,9 +93,9 @@ func CreateTestEnvironmentInTeam(a *app.App, c *request.Context, client *model.C
 	numImages := utils.RandIntFromRange(rangePosts) / 4
 	for j := 0; j < numPosts; j++ {
 		user := users[utils.RandIntFromRange(utils.Range{Begin: 0, End: len(users) - 1})]
-		_, resp := client.LoginById(user.Id, UserPassword)
-		if resp.Error != nil {
-			return TeamEnvironment{}, resp.Error
+		_, _, err := client.LoginById(user.Id, UserPassword)
+		if err != nil {
+			return TeamEnvironment{}, err
 		}
 
 		for i, channel := range channels {

app/slashcommands/auto_teams.go

@@ -57,9 +57,9 @@ func (cfg *AutoTeamCreator) createRandomTeam() (*model.Team, error) {
 		Type:        model.TeamOpen,
 	}
 
-	createdTeam, resp := cfg.client.CreateTeam(team)
-	if resp.Error != nil {
-		return nil, resp.Error
+	createdTeam, _, err := cfg.client.CreateTeam(team)
+	if err != nil {
+		return nil, err
 	}
 	return createdTeam, nil
 }

app/slashcommands/auto_users.go

@@ -39,23 +39,23 @@ func NewAutoUserCreator(a *app.App, client *model.Client4, team *model.Team) *Au
 }
 
 // Basic test team and user so you always know one
-func CreateBasicUser(a *app.App, client *model.Client4) *model.AppError {
-	found, _ := client.TeamExists(BTestTeamName, "")
+func CreateBasicUser(a *app.App, client *model.Client4) error {
+	found, _, _ := client.TeamExists(BTestTeamName, "")
 	if found {
 		return nil
 	}
 
 	newteam := &model.Team{DisplayName: BTestTeamDisplayName, Name: BTestTeamName, Email: BTestTeamEmail, Type: BTestTeamType}
-	basicteam, resp := client.CreateTeam(newteam)
-	if resp.Error != nil {
-		return resp.Error
+	basicteam, _, err := client.CreateTeam(newteam)
+	if err != nil {
+		return err
 	}
 	newuser := &model.User{Email: BTestUserEmail, Nickname: BTestUserName, Password: BTestUserPassword}
-	ruser, resp := client.CreateUser(newuser)
-	if resp.Error != nil {
-		return resp.Error
+	ruser, _, err := client.CreateUser(newuser)
+	if err != nil {
+		return err
 	}
-	_, err := a.Srv().Store.User().VerifyEmail(ruser.Id, ruser.Email)
+	_, err = a.Srv().Store.User().VerifyEmail(ruser.Id, ruser.Email)
 	if err != nil {
 		return model.NewAppError("CreateBasicUser", "app.user.verify_email.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

app/slashcommands/command_loadtest.go

@@ -215,9 +215,9 @@ func (*LoadTestProvider) SetupCommand(a *app.App, c *request.Context, args *mode
 		if err := CreateBasicUser(a, client); err != nil {
 			return &model.CommandResponse{Text: "Failed to create testing environment", ResponseType: model.CommandResponseTypeEphemeral}, err
 		}
-		_, resp := client.Login(BTestUserEmail, BTestUserPassword)
-		if resp.Error != nil {
-			return &model.CommandResponse{Text: "Failed to create testing environment", ResponseType: model.CommandResponseTypeEphemeral}, resp.Error
+		_, _, err := client.Login(BTestUserEmail, BTestUserPassword)
+		if err != nil {
+			return &model.CommandResponse{Text: "Failed to create testing environment", ResponseType: model.CommandResponseTypeEphemeral}, err
 		}
 		environment, err := CreateTestEnvironmentWithTeams(
 			a,
@@ -443,18 +443,18 @@ func (*LoadTestProvider) PostCommand(a *app.App, args *model.CommandArgs, messag
 	}
 
 	client := model.NewAPIv4Client(args.SiteURL)
-	_, resp := client.LoginById(user.Id, passwd)
-	if resp.Error != nil {
-		return &model.CommandResponse{Text: "Failed to login a user", ResponseType: model.CommandResponseTypeEphemeral}, resp.Error
+	_, _, nErr := client.LoginById(user.Id, passwd)
+	if nErr != nil {
+		return &model.CommandResponse{Text: "Failed to login a user", ResponseType: model.CommandResponseTypeEphemeral}, nErr
 	}
 
 	post := &model.Post{
 		ChannelId: channel.Id,
 		Message:   textMessage,
 	}
-	_, resp = client.CreatePost(post)
-	if resp.Error != nil {
-		return &model.CommandResponse{Text: "Failed to create a post", ResponseType: model.CommandResponseTypeEphemeral}, resp.Error
+	_, _, nErr = client.CreatePost(post)
+	if nErr != nil {
+		return &model.CommandResponse{Text: "Failed to create a post", ResponseType: model.CommandResponseTypeEphemeral}, nErr
 	}
 
 	return &model.CommandResponse{Text: "Added a post to " + channel.DisplayName, ResponseType: model.CommandResponseTypeEphemeral}, nil