First, install Gutenberg.
Then either comment out this workaround or change the Jetpack version number to 5.2.2 or higher. We worked around this first issue in the latest version of Gutenberg (https://github.com/WordPress/gutenberg/pull/2229).
Then, open a new post in Gutenberg and add a "Classic Text" block to it.
This line in the new contact-form code throws an error, and either leaves the editor a totally blank screen or breaks the newly added "Classic Text" block as in this screenshot:

This is because the script that initializes grunionEditorView is only loaded on the post screen, but TinyMCE (with external plugins) can be loaded in other contexts too, such as Gutenberg.
Once that is fixed, we see the following additional error in the console, which doesn't appear to be actively breaking anything:


I have the same issue 
but I resolve it by remove this line form this file https://www.programsgulf.com/wp-content/plugins/jetpack/modules/contact-form/grunion-editor-view.php
if ( ! isset( $current_screen->id ) || $current_screen->base !== 'post' ) {
return;
a quick fix would be to remove this code (which would force the javascript stuff to be loaded on all the admin pages).
Related: #7490
I think this the same issue as #7600 as well.
Another case of this in 624508-zen
And another: 623561-zen (Live Composer)
Reported in 614048-zen
To add to the impacted plugins, VIP Liveblogging plugin.
627427-zen
Black Studio Tiny MCE plugin: https://github.com/Automattic/jetpack/issues/7573
Edit: Workaround here, copied from comment above:
https://wordpress.org/support/topic/5-2-breaks-text-and-tinymce-widgets/#post-9379121
I think a better temp workaround would be to not load any grunion scripts/styles, includng tinyMCE buttons, see the latest revision of this gist for how this can be done: https://gist.github.com/tyxla/1ff7abb1ba484ee25200a41e1df4d0c8/revisions
615710-zen - Reporting this issue with Visual Composer
@danjjohnson @tyxla: Simplest workaround for users will be to just install this plugin --
https://github.com/georgestephanis/disable-grunion-editor-view
Nice one @georgestephanis. That'll probably be the case for most of the users.
Still, in case folks want to use the contact form editor, they'll probably need to go with the other workaround, which doesn't fully disable it, but just improves it to not load its scripts unless necessary.
I've added the filter but it didn't seem to solve the problem for me. I see a fix is moving along, and I thank you for that.
Reported here: 638743-zen. Let them know a fix is in place and should be shipped with next version.
Reported here 639661-zen conflicting with event espresso plugin
adding 660475-zen - so we can keep track of users to notify after the fix is shipped.
660598-zen
Any idea when a fix/new release will be shipped? this issues is breaking a core functionality of our plugins (see #7600 reported about a month ago) and we fear that we will are likely to loose a lot of new users which do not turn to our support so that we can inform them about the available workarounds :-/
@robertharm The fix was released this past Tuesday. Everything should now work. Let us know if you continue to experience issues with the current version of Jetpack.
thanks - issues cannot be reproduced anymore since the jetpack update.