get_post_type_object has the wrong type of validator for its parameter

[kamilkecki]

https://core.trac.wordpress.org/browser/tags/5.3/src/wp-includes/post.php?rev=46727#L1228

get_post_type_object expects a post type as a string as its parameter, however it checks if the parameter is scalar or not and returns null if it is not a number.

[SergeyBiryukov]

Hi there, welcome to WordPress Trac! Thanks for the ticket.

Just adding a link to the related changeset here: [34100] / #30013.

[sebastienserre]

Change type of check to be sure params is a string

[huzaifaalmesbah]

Tested on before patch and with 49748.diff​ WordPress 7.0-alpha-61215-src.
get_post_type_object() returns an object for valid string inputs and null for all non-string values, so the issue is not reproducible functionally.

The behavior is already safe, but the validator still uses is_scalar() while the docblock specifies a string. Using is_string() would better match the documented contract and improve clarity/type safety.

Removing needs-testing and adding dev-feedback since this appears to be a minor code quality improvement and may need maintainer input.