Docs: Explicitly return null when documented instead of void in filesystem and category functions.

[huzaifaalmesbah]

The @return tags for these functions indicate they may return null.
This fixes "Missing return argument" warnings that PHPStan (level 1) and IDEs report when a bare return; is used in a function documented to return a typed value including null.

Affected Functions and Files

• WP_Filesystem() in wp-admin/includes/file.php
• delete_plugins() in wp-admin/includes/plugin.php (2 occurrences)
• delete_theme() in wp-admin/includes/theme.php (2 occurrences)
• get_category_by_path() in wp-includes/category.php

Details

In each case, the function's @return tag already documents null as a possible return value (e.g. @return bool|null|WP_Error), but the early exit paths used a bare return;, which implicitly returns void.

Related: Trac #64238

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props huzaifaalmesbah, westonruter, shailu25, mukesh27, noruzzaman.

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[github-actions]

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[westonruter]

Related: #8965

[westonruter]

LGTM

[shail-mehta]

LGTM 👍

[noruzzamans]

LGTM

[Copilot]

Pull request overview

This pull request fixes PHPStan level 1 warnings and IDE type checking issues by ensuring functions explicitly return null when documented to do so, rather than implicitly returning void via bare return; statements. This improves static analysis compatibility and code clarity for functions that already document null as a possible return type in their @return tags.

Changes:

• Updated six early exit points across four WordPress core functions to explicitly return null instead of using bare return; statements
• All affected functions already documented null as a valid return type in their PHPDoc @return tags
• Changes align function implementations with their existing documentation

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/wp-includes/category.php	Changed get_category_by_path() to explicitly return null when no categories are found
src/wp-admin/includes/theme.php	Changed delete_theme() to explicitly return null when filesystem credentials fail (2 occurrences)
src/wp-admin/includes/plugin.php	Changed delete_plugins() to explicitly return null when filesystem credentials fail (2 occurrences)
src/wp-admin/includes/file.php	Changed WP_Filesystem() to explicitly return null when filesystem method class file does not exist

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[westonruter]

Note: These fix PHPStan rule level 3 issues.

[westonruter]

Committed in r61716 (954c187)