Update script-loader.php

[kbiegert]

Prevent null pointer.

Trac ticket: ticket 56482

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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.

[github-actions]

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[costdev]

Thanks for the PR @kbiegert! I've left one small suggestion.

Can you also update the PR's description to include a link to the Trac ticket for this patch? Thanks!

[costdev]

Thanks for the quick update @kbiegert! Just a couple more suggestions 🙂

[costdev]

Rather than call get_current_screen() twice, can we add global $current_screen; at the top of the function (above the multiline comment, with a line break), and have both of these conditions use the $current_screen variable instead? The docblock for this function will also need to have a @global tag added:

* @since 5.9.1
*
* @global WP_Screen $current_screen WordPress current screen object.
*/

Also, can we replace the new condition with $current_screen instanceof WP_Screen? This will ensure that it's a WP_Screen object before attempting to call the ::is_block_editor() method in the last condition.

[costdev]

Actually, hold off on the above suggestion for now. Pinging @SergeyBiryukov for a second opinion on this.

Sergey, some files in Core have multiple calls to get_current_screen(). Normally, we'd avoid multiple function calls. Is this something we should avoid here, or is this an exception?

[jrfnl]

Looking at the contents of the get_current_screen() function, @costdev's suggestions make sense to me.

I'd also would like to see a test covering the originally reported issue (throwing an error on PHP 8.1 without the fix and passing with the fix).

[costdev]

Regarding the test: The function relies on is_admin(), which, based on its source will require WP_ADMIN to be defined in order to test this issue and fix.

WP_ADMIN isn't defined in the test suite, and doing so in this test would impact other tests (including for this function). Not sure how to proceed with that.

That said, here's two screenshots:

As-is:

With new condition:

[jrfnl]

Yes, you got a point about the define(). There are ways around it (run in separate process, run as separate test suite), but those are outside the scope of this particular fix.