Enhance Error Message for Meta Fields

[apermo]

https://core.trac.wordpress.org/browser/trunk/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php#L270

https://core.trac.wordpress.org/browser/trunk/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php#L283

https://core.trac.wordpress.org/browser/trunk/src/wp-includes/rest-api/fields/class-wp-rest-meta-fields.php#L333

<?php
return new WP_Error(
   'rest_meta_database_error',
   __( 'Could not update meta value in database.' ),
   array( 'key' => $name, 'status' => WP_Http::INTERNAL_SERVER_ERROR )
);
?>

These 3 Error messages are actually not helpful, if you submit multiple meta fields, you don't know (at least not on the remote site) which meta was throwing the error.

It would be more helpful/self explaining if the error message was more like:

sprintf( __( 'Could not update the meta value "%s" in database.' ), $meta_key ), 

this way you could directly tell which meta field is throwing the error.

[TimothyBlynJacobs]

I agree this would be a quite helpful improvement.

Considering some of the other metadata improvements planned for 5.3, milestoning for 5.3 as well.

[AkSDvP]

With reference to the above conversation, I have created a patch to change exception messages. Please find & review associated patch attached herewith.

[SergeyBiryukov]

In 45681:

REST API: Make "Could not update meta value in database" error messages more helpful.

Props apermo, AkSDvP.
Fixes #46252.