Currently closing game while network thread is waiting for something is
very bug-prone, since network thread may resume during shutdown and
access partially destroyed client state.
Now if exit has been requested, the very first step would be semi-
graceful shutdown of network thread (via exception throwing). This may
in theory skip some cleanup in non-RAII code, but since game is shutting
down this does not matters much.
This logic applies to:
- shutting down while network thread is waiting for dialogs
- shuttind down while network thread waiting for animations in combat
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