fix: stop vpn binary on startup failure (#150)

The vpn binary doesn't exit by itself on failure to avoid messing up RPC calls, so the parent process is expected to stop it.

Author: deansheather

Vpn.Service/Manager.cs

@@ -172,6 +172,10 @@ await _tunnelSupervisor.StartAsync(_config.TunnelBinaryPath, HandleTunnelRpcMess
                 if (reply.MsgCase != TunnelMessage.MsgOneofCase.Start)
                     throw new InvalidOperationException("Tunnel did not reply with a Start response");
 
+                // If the tunnel failed to start, stop the subprocess.
+                if (!reply.Start.Success)
+                    await _tunnelSupervisor.StopAsync(ct);
+
                 await BroadcastStatus(reply.Start.Success ? TunnelStatus.Started : TunnelStatus.Stopped, ct);
                 return reply.Start;
             }