Migrate multiples methods from ChannelStore to return error interface (#14708)

Automatic Merge

app/team.go

@@ -1008,9 +1008,15 @@ func (a *App) LeaveTeam(team *model.Team, user *model.User, requestorId string)
 		}
 	}
 
-	channel, err := a.Srv().Store.Channel().GetByName(team.Id, model.DEFAULT_CHANNEL, false)
-	if err != nil {
-		return err
+	channel, nErr := a.Srv().Store.Channel().GetByName(team.Id, model.DEFAULT_CHANNEL, false)
+	if nErr != nil {
+		var nfErr *store.ErrNotFound
+		switch {
+		case errors.As(nErr, &nfErr):
+			return model.NewAppError("LeaveTeam", "app.channel.get_by_name.missing.app_error", nil, nfErr.Error(), http.StatusNotFound)
+		default:
+			return model.NewAppError("LeaveTeam", "app.channel.get_by_name.existing.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+		}
 	}
 
 	if *a.Config().ServiceSettings.ExperimentalEnableDefaultChannelLeaveJoinMessages {