Not sure the root cause exactly, since the error is pretty vague, but since migrating to Foundry v12 this module throws the following error at startup and is unusable.
Uncaught TypeError: CONST.DRAWING_TYPES is undefined
[Detected 1 package: multilevel-tokens]
modules/multilevel-tokens/multilevel.js:18
Not sure the root cause exactly, since the error is pretty vague, but since migrating to Foundry v12 this module throws the following error at startup and is unusable.