refs #20478 [finc] bugfix: hide spinner on error fetching cover by ajax

themes/finc/js/covers.js

@@ -50,7 +50,8 @@ function loadCoverByElement(data, element) {
     method: 'GET',
     data: data,
     element: element,
-    success: coverCallback
+    success: coverCallback,
+    error: spinner.hide()
   });
 }