Validation error in HTML mode after modifying a html tag

[malinajirka]

Describe the bug
When I replace a valid tag in HTML mode with an invalid tag gutenberg displays validation error -> eg <p> with <p123>.

To Reproduce
Steps to reproduce the behavior:

1. Create a post in WPAndroid
2. Type "hello"
3. Switch to HTML
4. Edit <p> to <p123>
5. Click on title
6. Boom

Expected behavior
The app won't crash.

Screenshots

Smartphone (please complete the following information):

• Device: Emulator
• OS: Android API 29
• Version develop - 6e59663f8c0eda962c8a6fa0a45212fbd17942b1

[cameronvoell]

As I'm working on this, I just wanted to comment that since the exhibited behavior is actually a Block Validation error (which only show the red banner in develop mode) and not a crash, the behavior for users will not be a full fledged crash, but will actually show disappearing paragraph HTML (the invalid block still shows in visual mode) . There is still something interesting going on here that should be fixed, but it might not have the urgency expressed in the title of this issue, since it is not actually crashing for users. See behavior in non develop build in the following video.

[Tug]

Related issues on gutenberg:
WordPress/gutenberg#10980
WordPress/gutenberg#12275
WordPress/gutenberg#12350
WordPress/gutenberg#7604

[geriux]

I'm closing this PR due to its activity. Currently, there's no easy option to toggle between editors and now if you change the HTML markup and it's detected as invalid, the editor will show a placeholder with an option to attempt to recover it.

Please feel free to re-open it if we happen to get any user reports about it. Thanks!