Show loading errors as Alerts (#5736)

New: Improved page loading errors

frontend/src/Activity/Blocklist/Blocklist.js

@@ -1,5 +1,6 @@
 import PropTypes from 'prop-types';
 import React, { Component } from 'react';
+import Alert from 'Components/Alert';
 import LoadingIndicator from 'Components/Loading/LoadingIndicator';
 import ConfirmModal from 'Components/Modal/ConfirmModal';
 import PageContent from 'Components/Page/PageContent';
@@ -155,14 +156,14 @@ class Blocklist extends Component {
 
           {
             !isFetching && !!error &&
-              <div>Unable to load blocklist</div>
+              <Alert kind={kinds.DANGER}>Unable to load blocklist</Alert>
           }
 
           {
             isPopulated && !error && !items.length &&
-              <div>
+              <Alert kind={kinds.INFO}>
                 No history blocklist
-              </div>
+              </Alert>
           }
 
           {