Make sure NEI plugins are loaded before processing keybindings (#375)

NEI plugins are initialized in a separate thread. If this takes too long,
the client tick handler might already be running checking the keybindings
in KeyManager while a plugin calls API.addKeyBind() which can lead to a
CME.

Reported in https://github.com/GTNewHorizons/GT-New-Horizons-Modpack/issues/13292
Thanks to @Denostrov for helping me track this down.

src/main/java/codechicken/nei/ClientHandler.java

@@ -276,7 +276,11 @@ public class ClientHandler {
 
             if (!NEIClientConfig.isEnabled()) return;
 
-            KeyManager.tickKeyStates();
+            /*
+             * NEI plugins are loaded in a separate thread. Make sure loading them has finished otherwise a CME might
+             * occur in KeyManager if a plugin calls API.addKeyBind() during initialization.
+             */
+            if (NEIClientConfig.isLoaded()) KeyManager.tickKeyStates();
 
             NEIController.updateUnlimitedItems(mc.thePlayer.inventory);
             if (mc.currentScreen == null) NEIController.processCreativeCycling(mc.thePlayer.inventory);