Fix error handler

src/de/steamwar/bungeecore/Subserver.java

@@ -176,7 +176,6 @@ public class Subserver {
     }
 
     protected void register() {
-        synchronized (serverList) {
         if(ProxyServer.getInstance().getServers().containsKey(serverName)) {
             SecurityException e = new SecurityException("Server already registered: " + serverName);
             stop();
@@ -184,6 +183,7 @@ public class Subserver {
             throw e;
         }
 
+        synchronized (serverList) {
             ProxyServer.getInstance().getServers().put(serverName, server);
             serverList.add(this);
             infoToServer.put(server, this);