TypeError: canvas is null

[caewok]

Foundry 0.7.9, dnd5e 1.2.3, Firefox 84.0.2, Mac OS X 10.15.7, macro marker 1.0.6. I am getting the following error when first logging into the world. I suspect that for some reason the canvas is not yet ready, so a check for whether the canvas is defined may prevent this?

Uncaught TypeError: canvas is null
renderMarkers macro-marker.js:610
delayCallback/timers[callback.name]< macro-marker.js:645
setTimeout handlerdelayCallback macro-marker.js:645
macro-marker.js:878
_call foundry.js:2496
call foundry.js:2481
_render foundry.js:4547
render foundry.js:4479
initializeUI foundry.js:6642
setupGame foundry.js:6545
_initializeGameView foundry.js:7319
initialize foundry.js:6471
_call_wrapped wrapper.js:298
call_wrapper wrapper.js:389
o lib-wrapper.js:409
call_wrapper wrapper.js:421
🎁 lib-wrapper.js:1
foundry.js:7449
async foundry.js:7447
macro-marker.js:610:19
renderMarkers macro-marker.js:610
delayCallback/timers[callback.name]< macro-marker.js:645
(Async: setTimeout handler)
delayCallback macro-marker.js:645
macro-marker.js:878
_call foundry.js:2496
call foundry.js:2481
_render foundry.js:4547
AsyncFunctionNext self-hosted:674
(Async: async)
render foundry.js:4479
initializeUI foundry.js:6642
setupGame foundry.js:6545
InterpretGeneratorResume self-hosted:1468
AsyncFunctionNext self-hosted:674
(Async: async)
_initializeGameView foundry.js:7319
initialize foundry.js:6471
InterpretGeneratorResume self-hosted:1468
AsyncFunctionNext self-hosted:674
(Async: async)
_call_wrapped wrapper.js:298
call_wrapper wrapper.js:389
call_wrapper self-hosted:1265
o lib-wrapper.js:409
call_wrapper wrapper.js:421
call_wrapper self-hosted:1265
🎁@handler0(Game.prototype.initialize) wrapper.js:133
foundry.js:7449
AsyncFunctionNext self-hosted:674
(Async: async)
foundry.js:7447