[Glitch] Fix notifications about deleted reports not being also deleted

Port d2eb726962 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/notifications/components/admin_report.js

@@ -69,6 +69,10 @@ export default class AdminReport extends ImmutablePureComponent {
   render () {
     const { intl, account, notification, unread, report } = this.props;
 
+    if (!report) {
+      return null;
+    }
+
     //  Links to the display name.
     const displayName = account.get('display_name_html') || account.get('username');
     const link = (