Check if $category is object before outputting

[michalzuber]

After auto upgrade I got a Notice: Trying to get property of non-object in /wp-includes/category-template.php on line 238
with WP version 4.2.9
Upgrade was from 4.2.7 as I can remember.

[michalzuber]

Check if is object

[swissspidy]

Does this still occur using the latest version of WordPress (4.5.3) and 4.6 Beta 1?

[michalzuber]

Tried to migrate the database to use the same data with the new code (trunk) and it worked.
But it would be great to check before using the object. The same might happen and this prevents it. Surely this is only Notice and errors on production should be turned off so not a big issue.

[SergeyBiryukov]

The patch is for get_the_category_list(), which retrieves the $categories array via get_the_category().

get_the_category() always returns an array of objects, so if invalid data is encountered, it's likely because a plugin or theme did something wrong with the the_category_list, get_the_terms, or wp_get_object_terms filter, which would be a developer error.

I don't think we should hide developer errors, a notice seems perfectly fine here. Feel free to reopen if you can still reproduce the issue on a clean install with no plugins installed and a default theme activated.