session manager detect GUI already running and gracefully fail

[Desrever Nu]

currently throws an exception

12:35:32.992 [Thread-0] INFO  - >> Listening on 0.0.0.0:4567 [spark.webserver.SparkServer:121]
12:35:33.107 [Thread-0] WARN  - FAILED ServerConnector@338268d6{HTTP/1.1,[http/1.1]}{0.0.0.0:4567}: java.net.BindException: Address already in use [o.e.j.u.c.AbstractLifeCycle:212]
java.net.BindException: Address already in use