heartbeat leaks stream listeners

[higaski]

This callback currently runs every second. Each time it creates a new subscription without canceling the previous one. If the WebSocket ever closes, all listeners call ref.invalidate(z21ServiceProvider) at the same time...

Frontend/lib/main.dart

Lines 436 to 453 in 3bce612

	void _heartbeat(_) {
	final z21 = ref.read(z21ServiceProvider);
	z21.lanXGetStatus();
	// Recover after socket was closed server side
	z21.stream.listen(
	null,
	onError: (e) {
	debugPrint('Z21 stream onError $e');
	ref.invalidate(z21ServiceProvider);
	},
	onDone: () {
	debugPrint('Z21 stream onDone');
	ref.invalidate(z21ServiceProvider);
	},
	);
	}
	}