Fix some null returns from defaulted registries (#5235)

src/main/java/net/minecraftforge/registries/ForgeRegistry.java

@@ -212,7 +212,8 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
     @Override
     public ResourceLocation getKey(V value)
     {
-        return this.names.inverse().get(value);
+        ResourceLocation ret = this.names.inverse().get(value);
+        return ret == null ? this.defaultKey : ret;
     }
 
     @Override

src/main/java/net/minecraftforge/registries/NamespacedDefaultedWrapper.java

@@ -124,7 +124,7 @@ class NamespacedDefaultedWrapper<V extends IForgeRegistryEntry<V>> extends Regis
     public V getRandom(Random random)
     {
         Collection<V> values = this.delegate.getValues();
-        return values.stream().skip(random.nextInt(values.size())).findFirst().orElse(null);
+        return values.stream().skip(random.nextInt(values.size())).findFirst().orElse(this.delegate.getDefault());
     }
 
     @Override