make null before shutdown

src/main/java/me/cortex/voxy/commonImpl/VoxyCommon.java

@@ -7,6 +7,8 @@ import net.fabricmc.api.ModInitializer;
 import net.fabricmc.loader.api.FabricLoader;
 import net.fabricmc.loader.api.ModContainer;
 
+import java.lang.invoke.VarHandle;
+
 public class VoxyCommon implements ModInitializer {
     public static final String MOD_VERSION;
     public static final boolean IS_DEDICATED_SERVER;
@@ -64,8 +66,9 @@ public class VoxyCommon implements ModInitializer {
 
     public static void shutdownInstance() {
         if (INSTANCE != null) {
-            INSTANCE.shutdown();
-            INSTANCE = null;
+            var instance = INSTANCE;
+            INSTANCE = null;//Make it null before shutdown
+            instance.shutdown();
         }
     }