LibraryElements: Delete invalid connections before deleting element (#50519) (#51550)

(cherry picked from commit 189b7f9c0b)

Co-authored-by: kay delaney <45561153+kaydelaney@users.noreply.github.com>

pkg/services/libraryelements/database.go

@@ -27,6 +27,8 @@ SELECT DISTINCT
 	, (SELECT COUNT(connection_id) FROM ` + models.LibraryElementConnectionTableName + ` WHERE element_id = le.id AND kind=1) AS connected_dashboards`
 )
 
+const deleteInvalidConnections = "DELETE FROM library_element_connection WHERE connection_id IN (SELECT connection_id as id FROM library_element_connection WHERE element_id=? EXCEPT SELECT id from dashboard)"
+
 func getFromLibraryElementDTOWithMeta(dialect migrator.Dialect) string {
 	user := dialect.Quote("user")
 	userJoin := `
@@ -179,6 +181,12 @@ func (l *LibraryElementService) deleteLibraryElement(c context.Context, signedIn
 		if err := l.requirePermissionsOnFolder(c, signedInUser, element.FolderID); err != nil {
 			return err
 		}
+
+		// Delete any hanging/invalid connections
+		if _, err = session.Exec(deleteInvalidConnections, element.ID); err != nil {
+			return err
+		}
+
 		var connectionIDs []struct {
 			ConnectionID int64 `xorm:"connection_id"`
 		}