fix client crash when viewers is ejected and userlist is hidden

bigbluebutton-html5/imports/ui/components/chat/message-form/typing-indicator/container.jsx

@@ -47,7 +47,7 @@ export default withTracker(() => {
     },
   });
 
-  if (meeting.lockSettingsProps.hideUserList && currentUser.role === USER_CONFIG.role_viewer) {
+  if (meeting.lockSettingsProps.hideUserList && currentUser?.role === USER_CONFIG.role_viewer) {
     selector.role = { $ne: USER_CONFIG.role_viewer };
   }