Fix FluidStack.EMPTY always being null

[Jab125]

Closes #500 My fix adds a null check to FluidStack.EMPTY to see if it is null as shown below:

--- a/common/src/main/java/dev/architectury/fluid/FluidStack.java
+++ b/common/src/main/java/dev/architectury/fluid/FluidStack.java
@@ -43,7 +43,7 @@

 public final class FluidStack implements DataComponentHolder {
     private static final FluidStackAdapter<Object> ADAPTER = adapt(FluidStack::getValue, FluidStack::new);
-    private static final FluidStack EMPTY = create(Fluids.EMPTY, 0);
+    private static final FluidStack EMPTY = new FluidStack(() -> Fluids.EMPTY, 0, DataComponentPatch.EMPTY);
     public static final Codec<FluidStack> CODEC = ADAPTER.codec();
     public static final StreamCodec<RegistryFriendlyByteBuf, FluidStack> STREAM_CODEC = ADAPTER.streamCodec();

[shedaniel]

No but, the proper fix would be to make EMPTY not null