いつのまにか get_category_link が機能していない | WordPressのカスタマイズ

<nav id="navx4">
	<a href="#" id="navx4a">Gulls list</a>
	<ul id="taxlist">
		<?php
			$args = array(
				'orderby' => 'name',
				'number' => '',
				'taxonomy' => 'gull',//カスタム分類名
			);
			$gulls = get_categories( $args );
			foreach( $gulls as $val ) {
				$descrips = explode( ':', $val->description );
				echo '<li><a href="' . get_category_link( $val->term_id ) . '">' . $descrips[0] . ' (' . $val->count . ')</a></li>';
			}
		?>
	</ul>
</nav>

<nav id="navx4">
	<a href="#" id="navx4a">Gulls list</a>
	<ul id="taxlist">
		<?php
			$terms = get_terms( 'gull', 'orderby=name' );
			foreach ( $terms as $term ) {
				// この $term はオブジェクトなので、$taxonomy を指定しなくてよい。
				$term_link = get_term_link( $term );

				// エラーなら次のタームへ進む。
				if ( is_wp_error( $term_link ) ) {
					continue;
				}

				// リンクを取得できたのでプリントアウトする。
				$descrips = explode( ':', $term->description );
				echo '<li><a href="' . esc_url( $term_link ) . '">' . $descrips[0] . ' (' . $term->count . ')</a></li>';
			}
		?>
	</ul>
</nav>

<?php
	public static function get_instance( $term_id, $taxonomy = null ) {
		global $wpdb;

		$term_id = (int) $term_id;
		if ( ! $term_id ) {
			return false;
		}

		$_term = wp_cache_get( $term_id, 'terms' );

		// If there isn't a cached version, hit the database.
		if ( ! $_term || ( $taxonomy && $taxonomy !== $_term->taxonomy ) ) {
			// Any term found in the cache is not a match, so don't use it.
			$_term = false;

			// Grab all matching terms, in case any are shared between taxonomies.
			$terms = $wpdb->get_results( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE t.term_id = %d", $term_id ) );
			if ( ! $terms ) {
				return false;
			}
			・
			・
			↓続く
?>

<?php
	echo '<li><a href="http://strix.main.jp/?gull=' . $val->slug . '">' . $descrips[0] . ' (' . $val->count . ')</a></li>';
?>