web/elements: fix loading overlay not being removed on error

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

web/src/elements/forms/ModalForm.ts

@@ -35,6 +35,9 @@ export class ModalForm extends ModalButton {
                     composed: true,
                 }),
             );
+        }).catch((exc) => {
+            this.loading = false;
+            throw exc;
         });
     }