fix server crash when hub disconnects unexpectedly during program run

closes #160

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 ### Fixed
 
+- Fix invalid ble-server state when hub disconnects during program running (e.g. when battery is removed) (https://github.com/Novakasa/brickrail/issues/160).
 - Fix pybricks error with motors with rotation encoders in pybricks 3.3-stable (https://github.com/Novakasa/brickrail/issues/174).
 - Don't allow adding train to occupied block. This previously created invalid state.
 - Fixed Switches and Crossing motors invalidated port when renaming a hub (https://github.com/Novakasa/brickrail/issues/163)

ble-server/ble_hub.py

@@ -325,9 +325,15 @@ async def run(self, program=None, wait=False, skip_download=False):
                 program = str(Path(__file__).parent / "hub_programs" / f"{program}.py")
 
         async def run_coroutine():
-            await self.hub._wait_for_user_program_stop()
-            self.program_stopped.set()
-            self.to_out_queue("program_stopped", None)
+            try:
+                await self.hub._wait_for_user_program_stop()
+            except Exception as err:
+                self.to_out_queue("program_error", repr(err))
+            finally:
+                self.program_stopped.set()
+                self.to_out_queue("program_stopped", None)
+                if not self.hub.client.is_connected:
+                    self.to_out_queue("disconnected", None)
 
         async def output_loop():
             while True: