"Error bundling site" when trying to edit "Add HTML" app

Steps to reproduce:

  1. Click edit install of “Add HTML” app
  2. Wait until everything loads incl. preview
  3. Edit HTML of first of 2 blocks
  4. Press “Save changes on 2 parts”
  5. Confirm email address sharing
  6. Wait

Actual result:
“An error occurred while trying to install the app: Error bundling site”

Expected result:
It works

Today it works again…weird.