Hi,
When loading my game, I get this error - any tips on what to do?
Failed to render WebGL canvas. Cannot set properties of null
Heya 
It sounds like there might be an issue with hardware acceleration. I’d recommend following this guide to enable hardware acceleration.
Then, try launching the world in Safe Configuration to make sure there aren’t any module errors preventing the world from loading in. If there are, you might need to disable some modules.
You might also be able to see more error information in your dev tools console (F12) 
Hope that helps!
Let us know if you still run into the error and post a screenshot if you can, that’ll help!