Unused variables in wp-includes/rest-api/*.php files

[antonvlasenko]

After inspecting the code in the wp-includes/rest-api/ files, the following minor issues have been identified:

• unused variables;
• incorrect @return type in the DocBlocks;
• typos;
• incorrect variable passed to the wp_parse_str() function in the WP_Rest_Server::serve_batch_request_v1() method.

Affected classes and files:

• WP_REST_Attachments_Controller;
• WP_REST_Block_Types_Controller;
• WP_REST_Post_Statuses_Controller;
• WP_REST_Posts_Controller;
• WP_REST_Taxonomies_Controller;
• WP_REST_Terms_Controller;
• WP_REST_Themes_Controller;
• WP_REST_URL_Details_Controller;
• WP_REST_Widgets_Controller;
• WP_REST_Post_Format_Search_Handler;
• WP_REST_Post_Search_Handler;
• WP_REST_Request;
• WP_REST_Server;
• rest-api.php.

Trac ticket: https://core.trac.wordpress.org/ticket/61593

[SergeyBiryukov]

In 58688:

REST API: Correct variable type in WP_Rest_Server::serve_batch_request_v1().

wp_parse_str() expects an array as the second parameter.

Follow-up to [49252].

Props antonvlasenko.
See #61593.

[SergeyBiryukov]

In 58694:

REST API: Remove a few unused variables in foreach loops.

Follow-up to [38832], [48173], [49132], [49925].

Props antonvlasenko.
See #61593.

[SergeyBiryukov]

In 58704:

Docs: Correct @return values for a few REST API class methods.

Includes listing the expected type first, instead of WP_Error.

Follow-up to [39031], [39033], [46696], [49927], [49929], [50993], [51286], [51973], [52079], [52286], [53152], [56415].

Props antonvlasenko.
See #61593.

[antonvlasenko]

Thank you for handling this ticket.
Next time, I'll ensure PRs are split by the type of changes they introduce.

[SergeyBiryukov]

In 58706:

Docs: Fix typos in various REST API DocBlocks and comments.

Follow-up to [34928], [43739], [46422], [50717], [51973], [54528].

Props antonvlasenko.
Fixes #61593.

Thanks for the PR! Merged in r58688, r58694, r58704, and r58706.