Fixed members importer state after unknown API error

no issue

- Members importer returns to first state of uploader with file selection when unknown error happens during the upload. If the upload fails and 'summary' state is set, it leads to showing summary stas during 'customizing' state.

app/components/modal-import-members.js

@@ -333,7 +333,10 @@ export default ModalComponent.extend({
 
     _uploadFinished() {
         this.set('uploading', false);
-        this.set('summary', true);
+
+        if (!this.get('failureMessage')) {
+            this.set('summary', true);
+        }
     },
 
     _importValidationFailed(errors) {