Run following code and then click remove button.

<form action="

" method="post">
<input type="hidden" name="DeleteIDArray[]" value="158" />
<input type="submit" name="RemoveButton" value="Remove" />
</form>

Content action for RemoveButton has hard coded content object id and node id, however when content object with id = 1 is not found then fatal error appears

Fatal error: Call to a member function attribute() on a non-object in kernel\content\action.php on line 1042