Twenty Twenty-One: Dark Mode toggle is causing JavaScript error in block editor

[ocean90]

For some reasons the dark-mode-toggler.js from Twenty Twenty-One is also enqueued in the block editor if Dark Mode support is enabled. This is causing JavaScript errors if the window (not the editor itself) is scrolled.

Uncaught TypeError: Cannot read property 'classList' of null
    at checkScroll (dark-mode-toggler.js?ver=1.0.0:56)

To reproduce enable Dark Mode support in the Customizer and open the block editor. Now reduce the height of the window so that you're able to scroll the admin menu. Once you scroll you should see the JavaScript error from above in the console.

The script should either check that the toggle exists or better not enqueued in the block editor at all.

[mukesh27]

52473.diff​ patch fix the issue.

[justinahinon]

I can reproduce the issue on Safari.

After applying the patch the error is gone.

Adding the commit keyword to the ticket.

[desrosj]

In 50269:

Twenty Twenty-One: Prevent Dark Mode related JavaScript error.

This prevents an Uncaught TypeError in the block editor when scrolling caused by the absence of a #dark-mode-toggler element.

Props ocean90, mukesh27, justinahinon.
Fixes #52473.

[sannevndrmeulen]

I was able to reproduce this issue without the patch.
After applying the patch I've checked Google Chrome, Firefox, and Safari.
The JavaScript error is gone.

[tikifez]

Confirming the error is gone. (Firefox)

[tikifez]

Confirming the error is gone. (Chrome)

[tikifez]

Confirming the error is gone. (Safari)