lnwatcher: catch callback exceptions

Catch exceptions happening to callbacks to continue calling the
remaining callbacks. Otherwise if the first callback throws an exception
the remaining callbacks aren't going to be called.

electrum/lnwatcher.py

@@ -56,7 +56,10 @@ class LNWatcher(Logger, EventListener):
             self.logger.info("synchronizer not set yet")
             return
         for address, callback in list(self.callbacks.items()):
-            await callback()
+            try:
+                await callback()
+            except Exception:
+                self.logger.exception(f"LNWatcher callback failed {address=}")
         # send callback to GUI
         util.trigger_callback('wallet_updated', self.lnworker.wallet)