Fix nil dereference panic in SearchArchivedInTeam (#16064)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/sqlstore/channel_store.go

@@ -2544,15 +2544,19 @@ func (s SqlChannelStore) SearchArchivedInTeam(teamId string, term string, userId
 		"UserId": userId,
 	})
 
-	output := *publicChannels
-	output = append(output, *privateChannels...)
-
 	outputErr := publicErr
 	if privateErr != nil {
 		outputErr = privateErr
 	}
 
-	return &output, outputErr
+	if outputErr != nil {
+		return nil, outputErr
+	}
+
+	output := *publicChannels
+	output = append(output, *privateChannels...)
+
+	return &output, nil
 }
 
 func (s SqlChannelStore) SearchForUserInTeam(userId string, teamId string, term string, includeDeleted bool) (*model.ChannelList, error) {

store/storetest/channel_store.go

@@ -80,6 +80,7 @@ func TestChannelStore(t *testing.T, ss store.Store, s SqlSupplier) {
 	t.Run("GetGuestCount", func(t *testing.T) { testGetGuestCount(t, ss) })
 	t.Run("SearchMore", func(t *testing.T) { testChannelStoreSearchMore(t, ss) })
 	t.Run("SearchInTeam", func(t *testing.T) { testChannelStoreSearchInTeam(t, ss, s) })
+	t.Run("SearchArchivedInTeam", func(t *testing.T) { testChannelStoreSearchArchivedInTeam(t, ss, s) })
 	t.Run("SearchForUserInTeam", func(t *testing.T) { testChannelStoreSearchForUserInTeam(t, ss) })
 	t.Run("SearchAllChannels", func(t *testing.T) { testChannelStoreSearchAllChannels(t, ss) })
 	t.Run("GetMembersByIds", func(t *testing.T) { testChannelStoreGetMembersByIds(t, ss) })
@@ -4947,6 +4948,28 @@ func (s ByChannelDisplayName) Less(i, j int) bool {
 	return s[i].Id < s[j].Id
 }
 
+func testChannelStoreSearchArchivedInTeam(t *testing.T, ss store.Store, s SqlSupplier) {
+	teamId := model.NewId()
+	userId := model.NewId()
+
+	t.Run("empty result", func(t *testing.T) {
+		list, err := ss.Channel().SearchArchivedInTeam(teamId, "term", userId)
+		require.Nil(t, err)
+		require.NotNil(t, list)
+		require.Empty(t, list)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		// trigger a SQL error
+		s.GetMaster().Exec("ALTER TABLE Channels RENAME TO Channels_renamed")
+		defer s.GetMaster().Exec("ALTER TABLE Channels_renamed RENAME TO Channels")
+
+		list, err := ss.Channel().SearchArchivedInTeam(teamId, "term", userId)
+		require.NotNil(t, err)
+		require.Nil(t, list)
+	})
+}
+
 func testChannelStoreSearchInTeam(t *testing.T, ss store.Store, s SqlSupplier) {
 	teamId := model.NewId()
 	otherTeamId := model.NewId()