Classic Editor Visual Mode Broken by Gutenberg

[weavertheme]

Describe the bug
WordPress 4.9.6
Gutenberg 2.9.1

The Classic Visual Editor is broken ; displays only a white screen. Text view okay.

To Reproduce
Steps to reproduce the behavior:

1. Disable all plugins except Gutenberg.
2. Activate a Twenty-Something theme (I used Twenty Sixteen).
3. Open Dashboard : Pages, Select some page, and click Classic Editor
4. The Visual Editor show a white screen. Nothing editable.
5. Strange side effect: If you switch to Text View, content there. Switch back to Visual, see blank screen. Now switch BACK to Text View, and all the line breaks are gone - just run together HTML.

Expected behavior
Duh - the classic editor needs to work. Note that WP 4.9.6 updated TinyMCE.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: macOS
• Browser: Chrome, Firefox
• Version: latest

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context

• Please add the version of Gutenberg you are using in the description.
• To report a security issue, please visit the WordPress HackerOne program: https://hackerone.com/wordpress.

[karmatosed]

I can replicate this, thanks for reporting. This could be due to the latest version as I don't believe this was occurring earlier in the week.

[danielbachhuber]

Related #6809

[weavertheme]

2.9.1 seems to break WP 4.9.5 also, except even the Text View doesn't show there.