posting per xmlrpc - works, but gives errmsgs ala "invalid xml"

[steamedpenguin]

attempts:
a)newsgator 2.0.3.1 b2 plugin
b)jericho-0.7

[steamedpenguin]

Originally from Skippy submitted at steamedpenguin.com/mantis/

[sdevore]

I regularly get truncated responses when getting postTitles and categories via xmlrpc in some clients but not others

[michel v]

That should be fixed. Add a comment if that happens again, though.

This PR improves defensive handling in WP_REST_Request::sanitize_params()
by validating parameter types before applying sanitize callbacks.

Benefits:

• Prevents PHP warnings on malformed or unexpected input
• Ensures arrays are sanitized item-by-item
• Improves data integrity for REST API requests
• Aligns with secure coding practices in WordPress core