Fix 500 when a comment was deleted which has a notification (#17550)

* Fix 500 when a comment was deleted which has a notification

* Tolerate missing Comment in other places too

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/notification.go

@@ -434,7 +434,13 @@ func (n *Notification) loadComment(e db.Engine) (err error) {
 	if n.Comment == nil && n.CommentID != 0 {
 		n.Comment, err = getCommentByID(e, n.CommentID)
 		if err != nil {
-			return fmt.Errorf("GetCommentByID [%d] for issue ID [%d]: %v", n.CommentID, n.IssueID, err)
+			if IsErrCommentNotExist(err) {
+				return ErrCommentNotExist{
+					ID:      n.CommentID,
+					IssueID: n.IssueID,
+				}
+			}
+			return err
 		}
 	}
 	return nil
@@ -488,7 +494,7 @@ type NotificationList []*Notification
 func (nl NotificationList) LoadAttributes() (err error) {
 	for i := 0; i < len(nl); i++ {
 		err = nl[i].LoadAttributes()
-		if err != nil {
+		if err != nil && !IsErrCommentNotExist(err) {
 			return
 		}
 	}

routers/api/v1/notify/repo.go

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

routers/api/v1/notify/threads.go

@@ -40,7 +40,7 @@ func GetThread(ctx *context.APIContext) {
 	if n == nil {
 		return
 	}
-	if err := n.LoadAttributes(); err != nil {
+	if err := n.LoadAttributes(); err != nil && !models.IsErrCommentNotExist(err) {
 		ctx.InternalServerError(err)
 		return
 	}
@@ -92,7 +92,7 @@ func ReadThread(ctx *context.APIContext) {
 		ctx.InternalServerError(err)
 		return
 	}
-	if err = notif.LoadAttributes(); err != nil {
+	if err = notif.LoadAttributes(); err != nil && !models.IsErrCommentNotExist(err) {
 		ctx.InternalServerError(err)
 		return
 	}