Block-based widgets screen doesn't load in the admin

[dkotter]

Describe the bug

If using a theme that uses block-based widgets (which I believe is the default experience for widgets since WordPress 5.8) and you have IBM Watson NLU configured, the admin widget screen doesn't load. A JS error gets logged in the console that is the cause of the problem.

In the NLU class we load a JS file specific to the block editor. This file ends up calling wp.data.select( 'core/editor' ).isSavingPost() which I guess doesn't exist within the widgets screen so it throws a JS error and processing stops, which then prevents the rest of the screen from loading. If I comment out that wp_enqueue_script block, the screen then loads.

I think we just need to ensure isSavingPost exists before we call it or maybe there's a better way to wrap this functionality to ensure it never throws errors.

Steps to Reproduce

1. Ensure you're on the latest version of WordPress
2. Activate the Twenty-Twenty One theme (or another theme that uses widgets)
3. Configure the IBM Watson NLU provider
4. Go to the admin widgets screen and notice the page doesn't show anything and an error shows in the browser console log

Screenshots, screen recording, code snippet

No response

Environment information

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WordPress information

No response

Code of Conduct

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[jeffpaul]

Here's a video showing the issue from a user perspective: https://www.loom.com/share/0354ec183c4e423abe42cc3680e479d0?sid=d7a8856a-46ed-40ff-8ed2-65068ed4d2aa