diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/class-wp-error.php
--- a/wp/wp-includes/class-wp-error.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/class-wp-error.php	Mon Oct 14 17:39:30 2019 +0200
@@ -11,11 +11,10 @@
  * WordPress Error class.
  *
  * Container for checking for WordPress errors and error messages. Return
- * WP_Error and use {@link is_wp_error()} to check if this class is returned.
- * Many core WordPress functions pass this class in the event of an error and
+ * WP_Error and use is_wp_error() to check if this class is returned. Many
+ * core WordPress functions pass this class in the event of an error and
  * if not handled properly will result in code errors.
  *
- * @package WordPress
  * @since 2.1.0
  */
 class WP_Error {
@@ -66,7 +65,6 @@
 	 * Retrieve all error codes.
 	 *
 	 * @since 2.1.0
-	 * @access public
 	 *
 	 * @return array List of error codes, if available.
 	 */
@@ -81,7 +79,6 @@
 	 * Retrieve first error code available.
 	 *
 	 * @since 2.1.0
-	 * @access public
 	 *
 	 * @return string|int Empty string, if no error codes.
 	 */
@@ -144,7 +141,7 @@
 	 * @since 2.1.0
 	 *
 	 * @param string|int $code Optional. Error code.
-	 * @return mixed Null, if no errors.
+	 * @return mixed Error data, if it exists.
 	 */
 	public function get_error_data($code = '') {
 		if ( empty($code) )
@@ -152,14 +149,12 @@
 
 		if ( isset($this->error_data[$code]) )
 			return $this->error_data[$code];
-		return null;
 	}
 
 	/**
 	 * Add an error or append additional message to an existing error.
 	 *
 	 * @since 2.1.0
-	 * @access public
 	 *
 	 * @param string|int $code Error code.
 	 * @param string $message Error message.
@@ -203,17 +198,3 @@
 		unset( $this->error_data[ $code ] );
 	}
 }
-
-/**
- * Check whether variable is a WordPress Error.
- *
- * Returns true if $thing is an object of the WP_Error class.
- *
- * @since 2.1.0
- *
- * @param mixed $thing Check if unknown variable is a WP_Error object.
- * @return bool True, if WP_Error. False, if not WP_Error.
- */
-function is_wp_error( $thing ) {
-	return ( $thing instanceof WP_Error );
-}