Description

This issue was previously reported on Trac: https://core.trac.wordpress.org/ticket/55015

In configurations with multiple theme directories, we have a blank screen when loading the Site Editor.

This was also reported upstream on Bedrock repository: roots/bedrock#74

Step-by-step reproduction instructions

See the above Trac ticket for more information

Screenshots, screen recording, code snippet

No response

Environment info

• WordPress 5.9.2 without Gutenberg plugin activated
• configurations with multiple theme directories like Bedrock

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes