feat: crash game on biome id conflict

build.gradle

@@ -24,7 +24,7 @@ apply from: './gradle/scripts/mixins.gradle'
 sourceCompatibility = JavaVersion.VERSION_1_8
 targetCompatibility = JavaVersion.VERSION_1_8
 
-version = "1.2.0"
+version = "1.3.0"
 group= "dev.tilera.modding"
 archivesBaseName = "cwg"
 

src/main/java/dev/tilera/cwg/ClassicWorldgen.java

@@ -9,6 +9,7 @@ import cpw.mods.fml.common.eventhandler.SubscribeEvent;
 import dev.tilera.cwg.caves.MapGenCavesSwiss;
 import dev.tilera.cwg.command.CommandChangeWorld;
 import net.minecraft.world.WorldType;
+import net.minecraft.world.biome.BiomeGenBase;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.event.terraingen.InitMapGenEvent;
 
@@ -17,6 +18,7 @@ public class ClassicWorldgen {
 
     public static final WorldType CLASSIC = new WorldTypeClassic("onesix");
     public static WorldType USED = null;
+    public static BiomeGenBase[] biomeCache = new BiomeGenBase[256];
 
     @Mod.Instance
     public static ClassicWorldgen INSTANCE;

src/main/java/dev/tilera/cwg/mixins/MixinBiomeGenBase.java

@@ -4,6 +4,9 @@ import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Overwrite;
 import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.At;
 
 import dev.tilera.cwg.ClassicWorldgen;
 import net.minecraft.world.biome.BiomeGenBase;
@@ -18,6 +21,20 @@ public abstract class MixinBiomeGenBase {
     @Final
     protected static NoiseGeneratorPerlin temperatureNoise;
 
+    @Inject(method = "<init>(IZ)V", at = @At("TAIL"))
+    public void constructorHead(int id, boolean register, CallbackInfo ci) {
+       if (register) {
+          if (ClassicWorldgen.biomeCache.length > id) {
+             BiomeGenBase self = (BiomeGenBase)(Object)this;
+             if (ClassicWorldgen.biomeCache[id] != null && ClassicWorldgen.biomeCache[id] != self) {
+               throw new RuntimeException("Biome ID conflict: " + id + " : " + self.biomeName + " : " + ClassicWorldgen.biomeCache[id].biomeName);
+             } else {
+                ClassicWorldgen.biomeCache[id] = self;
+             }
+          }
+       }
+    }
+
     /**
      * @author tilera
      * @reason No snow on hills