asyncio.get_running_loop() raises RuntimeError when emit() is called
from a thread without an active event loop (e.g. when the disk space
check in project_manager triggers a log.warning notification from a
threadpool worker).
This causes a 500 Internal Server Error on project creation/open when
disk usage is high, instead of the intended warning notification.
Wrap the emit loop in try/except RuntimeError so that notifications
are silently dropped when no event loop is available, rather than
crashing the request.
Fixes#2502Fixes#2505
