const isAdmin = this.props.isAdmin()

public/react/src/modules/courses/members/teacherList.js

@@ -227,6 +227,7 @@ class studentsList extends Component{
   }
   componentWillUnmount() {
     off('addTeacherSuccess', this.addTeacherSuccessListener)
+    const isAdmin = this.props.isAdmin()
     isAdmin && off('updateNavSuccess', this.updateNavSuccess)
   }
   updateNavSuccess = () => {