message: RefNull may return any reference type.
diff: @@ -9348,8 +9348,10 @@ impl<'ctx, 'a> LLVMFunctionCodeGenerator<'ctx, 'a> {
  * Reference types.
  * https://github.com/WebAssembly/reference-types/blob/master/proposals/reference-types/Overview.md
  ***************************/
  - Operator::RefNull { .. } => {
  - self.state.push1(self.intrinsics.funcref_ty.const_null());
  + Operator::RefNull { ty } => {
  + let ty = wptype_to_type(ty).map_err(to_compile_error)?;
  + let ty = type_to_llvm(self.intrinsics, ty)?;
  + self.state.push1(ty.const_zero());
  }
  Operator::RefIsNull => {
  let value = self.state.pop1()?.into_pointer_value();
  