onClose

Registers "hooks" which should be called when this scope is "closed". The hooks are intended to remove the keys associated with this scope from any data structures they may be held in, to avoid leaking allocations.

Note that a key may be specialized with several scopes and the first scope to be closed will remove it from any associated data structures (conceptually the scope that a log site is called from is the intersection of all the currently active scopes which apply to it).