SessionStore migration (#15002)

* Finished

* Fiximports

* Fix i18n

app/notification_push.go

@@ -386,7 +386,12 @@ func (a *App) SendAckToPushProxy(ack *model.PushNotificationAck) error {
 }
 
 func (a *App) getMobileAppSessions(userId string) ([]*model.Session, *model.AppError) {
-	return a.Srv().Store.Session().GetSessionsWithActiveDeviceIds(userId)
+	sessions, err := a.Srv().Store.Session().GetSessionsWithActiveDeviceIds(userId)
+	if err != nil {
+		return nil, model.NewAppError("getMobileAppSessions", "app.session.get_sessions.app_error", nil, err.Error(), http.StatusInternalServerError)
+	}
+
+	return sessions, nil
 }
 
 func ShouldSendPushNotification(user *model.User, channelNotifyProps model.StringMap, wasMentioned bool, status *model.Status, post *model.Post) bool {