KeyError in LiveKit SDK room listener on track_unpublished event #747

Describe the bug
When a track_unpublished event is received for a publication that is no longer present in the participant's internal _track_publications map, the SDK raises an unhandled KeyError, which is logged as error running user callback for track_unpublished.

error running user callback for track_unpublished: room_handle: 4
track_unpublished {
  participant_identity: "participant_C7A33F70-..."
  publication_sid: "TR_ACUVxvupEqihta"
}
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/livekit/rtc/room.py", line 560, in _listen_task
    self._on_room_event(event.room_event)
  File "/usr/local/lib/python3.11/site-packages/livekit/rtc/room.py", line 626, in _on_room_event
    rpublication = rparticipant._track_publications.pop(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 'TR_ACUVxvupEqihta'

Server
livekit = "^1.0.12"
livekit-agents = "^1.2.18"

• Environment: EKS
• any other information about your deployment setup

Client

• SDK: ios

Origin: LiveKit RTC SDK (livekit/rtc/room.py)

A race condition in the SDK where a track_unpublished event is processed for a publication SID that has already been removed (e.g. participant disconnect / duplicate event). The .pop() call has no default, so a missing key raises KeyError.