Fix crash logging

SpigotCore_Main/src/de/steamwar/core/Core.java

@@ -143,7 +143,7 @@ public class Core extends JavaPlugin{
 	public void onDisable() {
 		TinyProtocol.instance.close();
 		errorHandler.unregister();
-		if(!standalone) {
+		if(!standalone && crashDetector.onMainThread()) {
 			Statement.close();
 		}
 	}

SpigotCore_Main/src/de/steamwar/core/CrashDetector.java

@@ -20,6 +20,7 @@
 package de.steamwar.core;
 
 import de.steamwar.sql.SWException;
+import de.steamwar.sql.Statement;
 import org.bukkit.Bukkit;
 
 import java.util.Arrays;
@@ -47,6 +48,10 @@ public class CrashDetector {
         watchdog.interrupt();
     }
 
+    public boolean onMainThread() {
+        return Thread.currentThread() == mainThread;
+    }
+
     private void run() {
         while (run) {
             long curTime = System.currentTimeMillis();
@@ -58,6 +63,7 @@ public class CrashDetector {
                     if(Core.getInstance().isEnabled()) {
                         Core.getInstance().onDisable();
                     }
+                    Statement.close();
                     //System.exit(0); Does freeze, potential freezing issues: ConsoleRestoreHook, ApplicationShutdownHooks or DeleteOnExitHook
                     Runtime.getRuntime().halt(0);
                 }