Error when selecting a scene in "switch to scene"

[ToonTalk]

This only happens if the switch to scene block is inside a custom block editor

Uncaught TypeError: Cannot read properties of null (reading 'scenes')
    at InputSlotMorph.scenesMenu (blocks.js?version=2023-02-26:11320:47)
    at InputSlotMorph.menuFromDict (blocks.js?version=2023-02-26:10620:36)
    at InputSlotMorph.dropDownMenu (blocks.js?version=2023-02-26:10554:21)
    at InputSlotMorph.mouseClickLeft (blocks.js?version=2023-02-26:11458:14)
    at HandMorph.processMouseUp (morphic.js?version=2023-01-31:11579:29)
    at HTMLCanvasElement.<anonymous> (morphic.js?version=2023-01-31:12390:23)

[jmoenig]

Thanks, Ken! Fixing...