The callbacks are scheduled to the API thread, but hooked up in BDL
load. This causes a potential case of cross-thread collection
enumeration.
I've tested and it seems like the schedule logic should be fine for
short term. Longer term, we probably want to re-think how this works so
background operations aren't performed on the `DrawableChannel` in the
first place (chat shouldn't have an overhead like this when not
visible).
Closes#11231.
For some reason, the default channel type (Public) caused the channel manager to attempt to connect to an API, which was null at that time, after hot reloading the test environment (via dynamic compilation). Changing the channel type seems to fix that.