Gutenberg v19.6.0-rc.2 Removes getCanvasMode()

[holdercp]

Quick summary

This is a defect discovered during testing the upcoming Gutenberg 19.6.0 release. It is not live.

The Gutenberg v19.6.0-rc.2 release removes the getCanvasMode() API in WordPress/gutenberg#66213 from the edit-site store. Several Calypso apps are using this API and are now unable to load with this GB version installed.

The following Calypso apps should be updated to determine the canvas state from the URL params as suggested in the GB PR:

• help-center
• wpcom-block-editor

Using the URL for this state is compatible with older GB releases so this can be deployed before v19.6.0 lands.

Related to Automattic/jetpack#39997

Steps to reproduce

1. Install GB v19.6.0-rc.2 on a site
2. Install a Full Site Edit theme
3. Navigate to Appearance -> Editor
4. Check console logs and notice errors relating to the help-center, wpcom-block-editor, and the Jetpack wpcom-block-editor-nux plugins
5. Notice the help center icon is missing
6. Click into the canvas to edit
7. Notice the errors in the UI

What you expected to happen

The mentioned plugins load as normal.

What actually happened

• Missing help icon
• Visible UI errors
• Console errors

Impact

All

Available workarounds?

There is no user impact

If the above answer is "Yes...", outline the workaround.

No response

Platform (Simple and/or Atomic)

Simple, Atomic

Logs or notes

No response

[obenland]

@holdercp Can this be closed now?