'Object reference not set to an instance of an object.' appears in Web Editor when trying to view any Profile Card for a specific class.

'Object reference not set to an instance of an object.' appears in Web Editor when trying to view any Profile Card for a specific class.

'Object reference not set to an instance of an object.' appears in Web Editor when trying to view any Profile Card for a specific class.

This occurs because of an issue with the Web Profile Card for that class.

Reset the Web Profile Card for that class and that will resolve the issue.