我有点纠结于以下错误

Illegal string offset \'taxonomy\' in ...  on line 175
Trying to get property of non-object in ... on line 177
Trying to get property of non-object in ... on line 178

function tax_cat_active( $output, $args ) {

  if(is_single()){
    global $post;

    $terms = get_the_terms( $post->ID, $args[\'taxonomy\'] );
    foreach( $terms as $term )
        if ( preg_match( \'#cat-item-\' . $term ->term_id . \'#\', $output ) )
            $output = str_replace(\'cat-item-\'.$term ->term_id, \'cat-item-\'.$term ->term_id . \' current-cat\', $output);
  }

  return $output;
}
add_filter( \'wp_list_categories\', \'tax_cat_active\', 10, 2 );