Improved interface detach on shared instance shutdown

RNS/Interfaces/TCPInterface.py

@@ -202,11 +202,13 @@ class TCPClientInterface(Interface):
                     self.detached = True
                     
                     try:
+                        if self.socket != None:
                             self.socket.shutdown(socket.SHUT_RDWR)
                     except Exception as e:
                         RNS.log("Error while shutting down socket for "+str(self)+": "+str(e))
 
                     try:
+                        if self.socket != None:
                             self.socket.close()
                     except Exception as e:
                         RNS.log("Error while closing socket for "+str(self)+": "+str(e))