If the camera track has already ended by the time the blur processor is
applied to it, MediaStreamTrackProcessor cannot be constructed and
setProcessor rejects. Both call sites used `void`, so this surfaced as
Unhandled promise rejection: TypeError: Failed to construct
'MediaStreamTrackProcessor': Input track cannot be ended
(element-call-rageshakes#17225). Skip ended tracks, and catch and log
processor attach/detach failures instead of leaking them.
Matthew Hodgson
2e5b5cb186