Fix crash caused by PonySkullRenderer.resolve() being called too early.

src/main/java/com/minelittlepony/client/MineLittlePony.java

@@ -93,6 +93,9 @@ public class MineLittlePony implements ClientModInitializer {
         ClientTickCallback.EVENT.register(this::onTick);
         ClientReadyCallback.EVENT.register(this::onClientReady);
         ScreenInitCallback.EVENT.register(this::onScreenInit);
+        if (config.ponyskulls.get()) {
+            PonySkullRenderer.resolve();
+        }
 
         if (FabricLoader.getInstance().isModLoaded("hdskins")) {
             IndirectHDSkins.initialize();
@@ -135,8 +138,6 @@ public class MineLittlePony implements ClientModInitializer {
                 }
             }
         }
-
-        PonySkullRenderer.resolve();
     }
 
     private void onScreenInit(Screen screen, ScreenInitCallback.ButtonList buttons) {

src/main/java/com/minelittlepony/client/gui/GuiPonySettings.java

@@ -1,5 +1,6 @@
 package com.minelittlepony.client.gui;
 
+import com.minelittlepony.client.render.tileentities.skull.PonySkullRenderer;
 import net.minecraft.client.gui.screen.Screen;
 import net.minecraft.client.resource.language.I18n;
 import net.minecraft.text.LiteralText;
@@ -155,5 +156,7 @@ public class GuiPonySettings extends GameGui {
     public void onClose() {
         super.onClose();
         config.save();
+
+        PonySkullRenderer.resolve();
     }
 }

src/main/java/com/minelittlepony/client/render/layer/LayerPonyCustomHead.java

@@ -3,7 +3,6 @@ package com.minelittlepony.client.render.layer;
 import com.minelittlepony.client.model.AbstractPonyModel;
 import com.minelittlepony.client.model.IPonyModel;
 import com.minelittlepony.client.render.IPonyRender;
-import com.minelittlepony.client.render.tileentities.skull.PonySkullRenderer;
 import com.minelittlepony.model.BodyPart;
 import com.mojang.authlib.GameProfile;
 
@@ -11,6 +10,7 @@ import net.minecraft.block.AbstractSkullBlock;
 import net.minecraft.block.SkullBlock.SkullType;
 import net.minecraft.block.entity.SkullBlockEntity;
 import net.minecraft.client.MinecraftClient;
+import net.minecraft.client.render.block.entity.SkullBlockEntityRenderer;
 import net.minecraft.client.render.entity.model.EntityModel;
 import net.minecraft.client.render.model.json.ModelTransformation;
 import net.minecraft.entity.EquipmentSlot;
@@ -97,7 +97,7 @@ public class LayerPonyCustomHead<T extends LivingEntity, M extends EntityModel<T
 
         SkullType type = ((AbstractSkullBlock) ((BlockItem) itemstack.getItem()).getBlock()).getSkullType();
 
-        PonySkullRenderer.resolve().render(-0.5F, 0, -0.5F, null, 180, type, profile, -1, limbSwing);
+        SkullBlockEntityRenderer.INSTANCE.render(-0.5F, 0, -0.5F, null, 180, type, profile, -1, limbSwing);
     }
 
     @Override

src/main/java/com/minelittlepony/client/render/tileentities/skull/PonySkullRenderer.java

@@ -28,7 +28,7 @@ import static com.mojang.blaze3d.platform.GlStateManager.*;
  */
 public class PonySkullRenderer extends SkullBlockEntityRenderer {
 
-    public static PonySkullRenderer ponyInstance = new PonySkullRenderer();
+    private static final PonySkullRenderer ponyInstance = new PonySkullRenderer();
     private static SkullBlockEntityRenderer backup = null;
 
     private static final Map<SkullBlock.SkullType, ISkull> skullMap = SystemUtil.consume(Maps.newHashMap(), (skullMap) -> {
@@ -44,27 +44,20 @@ public class PonySkullRenderer extends SkullBlockEntityRenderer {
      *
      * Original/Existing renderer is stored to a backup variable as a fallback in case of mods.
      */
-    public static SkullBlockEntityRenderer resolve() {
+    public static void resolve() {
         if (MineLittlePony.getInstance().getConfig().ponyskulls.get()) {
             if (!(INSTANCE instanceof PonySkullRenderer)) {
                 backup = INSTANCE;
                 BlockEntityRendererRegistry.INSTANCE.register(SkullBlockEntity.class, ponyInstance);
-                INSTANCE = ponyInstance;
             }
         } else {
             if ((INSTANCE instanceof PonySkullRenderer)) {
-                ponyInstance = (PonySkullRenderer) INSTANCE;
                 if (backup == null) {
                     backup = new SkullBlockEntityRenderer();
                 }
                 BlockEntityRendererRegistry.INSTANCE.register(SkullBlockEntity.class, backup);
-                INSTANCE = backup;
             }
         }
-
-        INSTANCE.setRenderManager(BlockEntityRenderDispatcher.INSTANCE);
-
-        return INSTANCE;
     }
 
     @Override