Make sure we don't call exitProcess() if the system is already terminating

Server/src/main/java/core/game/system/SystemShutdownHook.java

@@ -14,6 +14,6 @@ public final class SystemShutdownHook implements Runnable {
 			return;
 		}
 		SystemLogger.logInfo("[SystemShutdownHook] Terminating...");
-		SystemManager.getTerminator().terminate();
+		SystemManager.flag(SystemState.TERMINATED);
 	}
 }

Server/src/main/kotlin/rs09/Server.kt

@@ -109,7 +109,8 @@ object Server {
                         it.flush()
                         it.close()
                     }
-                    exitProcess(0)
+                    if(!SystemManager.isTerminated())
+                        exitProcess(0)
                 }
                 delay(625)
             }