[mpeshev]

When $_POST['user_login'] is not set while adding a user, edit_user() never set the user_login property, so the later checks read an undefined property (PHP warnings) and the "Please enter a username" error was not added. This sets it to an empty string in that case, so the existing validation reports the missing username: the same approach as 36303.patch on the ticket, with a unit test.

Trac ticket: https://core.trac.wordpress.org/ticket/36303

Testing

• vendor/bin/phpunit --filter test_edit_user_missing_user_login fails without the patch with Undefined property: stdClass::$user_login and passes with it.
• vendor/bin/phpunit --group user passes (1464 tests).

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Opus 5.5
Used for: reproducing the warnings in trunk, drafting the fix and test, and running them. I reviewed every line.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

🤖 Generated with Claude Code

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs.

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

Props nofearinc.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

---

Props Bot commands

You can trigger Props Bot actions by commenting on this PR:

• @propsbot add <username> to give props to a GitHub user. Requires write access.
• @propsbot remove <username> to leave a user out of the props. Requires write access.
• @propsbot refresh to refresh this list. Adding the props-bot label works too.

[github-actions]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Some things to be aware of

• All changes will be lost when closing a tab with a Playground instance.
• All changes will be lost when refreshing the page.
• A fresh instance is created each time the link below is clicked.
• Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance,
  it's possible that the most recent build failed, or has not completed. Check the list of workflow runs to be sure.

For more details about these limitations and more, check out the Limitations page in the WordPress Playground documentation.

Test this pull request with WordPress Playground.