comments_array filter issue

I am trying to parse comments using the filter ‘comments_array’ when I enable the filter with;

add_filter( 'comments_array', 'jshout_comments' );

All I am doing initially is;

function jshout_comments( $comments, $id )
{
	return( $comments );
}

What happens is that all themes (incl twenty_*) immediately break, I have debug on and nothing is reported it is almost as though a ‘die()’ is happening. If I comment out add filter all works, uncomment the theme breaks .. stops all output.

Any ideas to help track it down would be appreciated.

Larry