Coding Standards: Remove extra check in wp_authenticate_application_password().

This commit removes an unnecessary `is_wp_error()` check, as the `WP_Error` instance is created earlier in the method, and the only mutability is whether the instance actually `::has_errors()`.

Follow-up to [49109].

Props justlevine.
See #63268.

git-svn-id: https://develop.svn.wordpress.org/trunk@60310 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/user.php

@@ -477,7 +477,7 @@ function wp_authenticate_application_password(
 		 */
 		do_action( 'wp_authenticate_application_password_errors', $error, $user, $item, $password );
 
-		if ( is_wp_error( $error ) && $error->has_errors() ) {
+		if ( $error->has_errors() ) {
 			/** This action is documented in wp-includes/user.php */
 			do_action( 'application_password_failed_authentication', $error );