Hook up the biome registry.

worldedit-core/src/main/resources/com/sk89q/worldedit/world/registry/legacy.json

@@ -1785,7 +1785,7 @@
     "48:0": "minecraft:mossy_cobblestone",
     "49:0": "minecraft:obsidian",
     "50:0": "minecraft:torch",
-    "52:0": "minecraft:mob_spawner",
+    "52:0": "minecraft:spawner",
     "53:0": "minecraft:oak_stairs",
     "54:0": "minecraft:chest",
     "56:0": "minecraft:diamond_ore",

worldedit-forge/src/main/java/com/sk89q/worldedit/forge/ForgeWorldEdit.java

@@ -33,6 +33,7 @@ import com.sk89q.worldedit.forge.net.handler.InternalPacketHandler;
 import com.sk89q.worldedit.forge.net.handler.WECUIPacketHandler;
 import com.sk89q.worldedit.forge.net.packet.LeftClickAirEventMessage;
 import com.sk89q.worldedit.util.Location;
+import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockCategory;
 import com.sk89q.worldedit.world.block.BlockType;
 import com.sk89q.worldedit.world.entity.EntityType;
@@ -186,6 +187,12 @@ public class ForgeWorldEdit {
                 EntityType.REGISTRY.register(name.toString(), new EntityType(name.toString()));
             }
         }
+        // Biomes
+        for (ResourceLocation name : ForgeRegistries.BIOMES.getKeys()) {
+            if (BiomeType.REGISTRY.get(name.toString()) == null) {
+                BiomeType.REGISTRY.register(name.toString(), new BiomeType(name.toString()));
+            }
+        }
         // Tags
         for (ResourceLocation name : BlockTags.getCollection().getRegisteredTags()) {
             if (BlockCategory.REGISTRY.get(name.toString()) == null) {