ignore missing comment for user notifications (#18954)

* ignore missing comment for user notifications

* instead fix bug in notifications model

* use local variable instead

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

routers/api/v1/notify/repo.go

@@ -121,7 +121,7 @@ func ListRepoNotifications(ctx *context.APIContext) {
 		return
 	}
 	err = nl.LoadAttributes()
-	if err != nil && !models.IsErrCommentNotExist(err) {
+	if err != nil {
 		ctx.InternalServerError(err)
 		return
 	}