Adds check for term before capability check

[msawicki]

Description of the Change

The action_sync_on_object_update method that's hooked into set_object_terms needs to be able to handle an array of term slugs. The reason being is that wp_set_object_terms()'s second parameter can be string|int|array. See docs. When a string is passed, wp_set_object_terms wraps it in an array, thus becoming an array of slugs that's later passed to set_object_terms. Using the term_exists() function here provides some flexibility since it accepts ID, slug, or name. Without this check, when a slug is passed into wp_set_object_terms() (Polylang does this when setting a language) it will throw a php Notice "Trying to get property 'term_id' of non-object" in SyncManager.php:110. This can be replicated with Polylang and ElasticPress installed with the Terms Feature enabled. From there, creating a new post will give you a php notice noted above.

I don't think there is a current issue files for this but please let me know if I'm incorrect and I'll link the two.

Alternate Designs

NA

Benefits

No php Notices

Possible Drawbacks

Extra database queries in the term_exists() function but I think this a cleaner approach than various type checks.

Verification Process

I made this change in my local environment and ran several check/tests updating and adding new post content.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

NA

Changelog Entry

Added a check for term exists to get the term id by slug, id or name before a capabilities check is done.

[felipeelia]

Hi @msawicki, first of all, thank you very much for the Pull Request! To make the code comply with our standards, do you mind changing
if( ! $term_info ) {
to
if ( ! $term_info ) {
?
We've also merged a few things recently, so it would be great if you could update your branch as well.

Thanks!

[msawicki]

@felipeelia Updated! Thanks for the feedback.