FSR can lock editor if started when domain reload in progress

Needs confirmation.

File watchers are triggered outside of main thread and potentially code could run even if Unity is doing main reload?

Not sure why that'd lock reloading.

There are some settings in code that'll use LockAssemblyReload - maybe that somehow could contribute?

Start by reproducing the lock while Unity's domain reload is in progress, focusing on the file watchers that may run outside the main thread. Inspect the code paths using LockAssemblyReload and determine whether they can overlap with reload. Done means confirming the cause and documenting or fixing the locking behavior, with a reliable reproduction.

Written by the indexing model from the issue text.