Make Mixin Classes Abstract

src/main/java/noppes/npcs/mixin/MixinEntityRenderer.java

@@ -11,7 +11,7 @@ import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 @Mixin(value = EntityRenderer.class)
-public class MixinEntityRenderer {
+public abstract class MixinEntityRenderer {
 
     @Inject(method = "renderWorld", at = @At(value = "RETURN"))
     private void renderFirstPersonOverlays(float p_78476_1_, long p_78476_2_, CallbackInfo callbackInfo)

src/main/java/noppes/npcs/mixin/MixinItemRenderer.java

@@ -45,7 +45,7 @@ import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import static net.minecraftforge.client.IItemRenderer.ItemRenderType.EQUIPPED_FIRST_PERSON;
 
 @Mixin(ItemRenderer.class)
-public class MixinItemRenderer {
+public abstract class MixinItemRenderer {
 
     @Inject(method = "renderItemInFirstPerson", at = @At(value = "HEAD"), cancellable = true)
     public void renderItemInFirstPerson(float p_78440_1_, CallbackInfo callbackInfo)

src/main/java/noppes/npcs/mixin/MixinRenderPlayer.java

@@ -19,7 +19,7 @@ import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 @Mixin(value = RenderPlayer.class)
-public class MixinRenderPlayer {
+public abstract class MixinRenderPlayer {
 
     @SideOnly(Side.CLIENT)
     @Inject(method = "rotateCorpse*", at = @At(value = "TAIL"))