Fix: only parse custom field queries when valid (#9384)

src-ui/src/app/components/document-list/filter-editor/filter-editor.component.ts

@@ -872,7 +872,7 @@ export class FilterEditorComponent
     let queries = this.customFieldQueriesModel.queries.map((query) =>
       query.serialize()
     )
-    if (queries.length > 0) {
+    if (queries.length > 0 && this.customFieldQueriesModel.isValid()) {
       filterRules.push({
         rule_type: FILTER_CUSTOM_FIELDS_QUERY,
         value: JSON.stringify(queries[0]),