check release publisher exists (#14375)

fixes #14365
was silently fixed in the feature PR #12096 for v1.14

models/release.go

@@ -54,7 +54,11 @@ func (r *Release) loadAttributes(e Engine) error {
 	if r.Publisher == nil {
 		r.Publisher, err = getUserByID(e, r.PublisherID)
 		if err != nil {
-			return err
+			if IsErrUserNotExist(err) {
+				r.Publisher = NewGhostUser()
+			} else {
+				return err
+			}
 		}
 	}
 	return getReleaseAttachments(e, r)