Customizer: Star Ratings block breaks widgets section

[KokkieH]

Quick summary

Trying to add or edit a Star Ratings block in the Customizer widget area leads to an "unexpected error"

Steps to reproduce

1. Go to Appearance ->Customize ->Widgets
2. Add a Star Ratings block

Optionally, try editing the Star Ratings block that's already present in the widget area

What you expected to happen

For the block to be added/ to be able to edit the block.

What actually happened

The widget editor disappears and is replaced by this error message:

Clicking the Copy Error button gives the following:

Bj@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:7:29846
Qj@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:9:876
unstable_runWithPriority@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react.min.755b0ae9.js?m=1624062436h:5:3609
Za@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:6:12302
eb@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:8:6341
gf@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:8:2337
$g/<@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:6:12524
unstable_runWithPriority@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react.min.755b0ae9.js?m=1624062436h:5:3609
Za@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:6:12302
$g@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:6:12472
ja@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:6:12405
@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:10:14674
Ki@https://s0.wp.com/wp-content/plugins/gutenberg-core/v12.0.1/vendor/react-dom.min.edd8b7a6.js?m=1624062436h:5:1411

So it appears it's something in Gutenberg 12.0 causing this.

Context

Reported by a user trying to remove the widget from their site in https://wordpress.com/forums/topic/having-trouble-deleting-a-widget/?view=all

Operating System

No response

Browser

Google Chrome/Chromium, Mozilla Firefox

Simple, Atomic or both?

Simple, Atomic

Theme-specific issue?

Can replicate on multiple themes

Other notes

No response

Reproducibility

Consistent

Severity

Some (< 50%)

Available workarounds?

Yes, easy to implement

Workaround details

The widget works normally if added/edited from /wp-admin/widgets.php

[csonnek]

User provided a screenshot and offered the following:

Sorry for the double post, but if it will help, I wanted to let you know I also cleared the cache from Chrome through my Settings app (system) too after it still wouldn’t load.

Let us know if you need anything else from this person.

[KokkieH]

Additional info: the WP-Admin Widgets page also doesn't work for them using Chrome 96 on an Android device. I've asked them to try in a desktop browser instead.

I've confirmed that /wp-admin/widgets.php doesn't appear to work at all in Chrome on Android, but that's a separate issue from the star ratings block causing the Customizer widget area to crash.

[KokkieH]

Appears this is similar to #56564