Return a WP_Error if an empty name is provided when registering a taxonomy.

Fixes #31135
Props tyxla, MikeHansenMe


git-svn-id: https://develop.svn.wordpress.org/trunk@31449 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/taxonomy.php

@@ -153,6 +153,15 @@ class Tests_Taxonomy extends WP_UnitTestCase {
 		unset($GLOBALS['wp_taxonomies'][$tax]);
 	}
 
+	/**
+	 * @ticket 31135
+	 *
+	 * @expectedIncorrectUsage register_taxonomy
+	 */
+	function test_register_short_taxonomy() {
+		$this->assertInstanceOf( 'WP_Error', register_taxonomy( '', 'post', array() ) );
+	}
+
 	/**
 	 * @ticket 21593
 	 *