List block: Sometimes pasting into a list is ignored

[bobbingwide]

Description

Sometimes, pasting content into a list results in no content being pasted.

Please see the video

Step-by-step reproduction instructions

1. Create a list block
2. Copy some stuff from another page ( eg. a GitHub issue )
3. Attempt to paste into the list block
4. Sometimes it works, sometimes it doesn't

Expected behaviour

Content should be pasted everytime.

Actual behaviour

Sometimes the content doesn't appear to be pasted.

Screenshots or screen recording (optional)

Enable sound to hear me describe my steps.
https://user-images.githubusercontent.com/2474435/120866550-1694b280-c588-11eb-932d-028e6ba102cf.mp4

Code snippet (optional)

WordPress information

• WordPress version: 5.7.2
• Gutenberg version: 10.7.1
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Yes

Device information

• Device: Desktop
• Operating system: Windows 10
• Browser: Chrome

[bobbingwide]

This may be relevant
Uncaught Type error: Cannot read property 'length' of undefined.

[johngodley]

I'm also seeing this, although it seems to trigger every time. I think it might be fixed by #32527

[colorful-tones]

I just hit this bug. I hope #32527 fixes it 🤞

[talldan]

The description in #32590 might help with reproducing. It seems to happen whenever pasting into a new list item, but as soon as text is entered pasting works ok.

[mrfoxtalbot]

I have noticed a very similar issue that is affecting the quote block.

With the plugin active (10.8), it will not be possible to add new paragraphs into a quote block. This was reported originally here Automattic/wp-calypso#53591

@colorful-tones, do you think that #32527 will also fix this in the case of quote blocks, or was it just for list blocks? Thank you!

[talldan]

#32839 reports that the same issue happens in the paragraph block after using shift+enter to add a line break.

When testing I saw the same error message:

Uncaught TypeError: Cannot read property 'length' of undefined
    at addActiveFormats (utils.js:8)
    at HTMLParagraphElement._onPaste (use-paste-handler.js:190)

[talldan]

Looks like this was fixed yesterday by #32527