Fix fluid builder bucket

Author: IThundxr

src/main/java/com/tterrag/registrate/builders/FluidBuilder.java

@@ -500,7 +500,7 @@ public <I extends BucketItem> ItemBuilder<I, FluidBuilder<T, P>> bucket(NonNullB
         if (source == null) {
             throw new IllegalStateException("Cannot create a bucket before creating a source block");
         }
-        return getOwner().<I, FluidBuilder<T, P>>item(this, bucketName, p -> factory.apply(get().get(), p))
+        return getOwner().<I, FluidBuilder<T, P>>item(this, bucketName, p -> factory.apply(source.get(), p))
             .properties(p -> p.craftRemainder(Items.BUCKET).stacksTo(1))
             .model((ctx, prov) -> prov.generated(ctx::getEntry, ResourceLocation.fromNamespaceAndPath(getOwner().getModid(), "item/" + bucketName)));
     }