message: Fix DiffArray::index() return type
diff: @@ -1763,7 +1763,7 @@ struct DiffArray : ArrayBase<value_t<Type_>, is_mask_v<Type_>, DiffArray<Type_>>
  m_value.init_(size);
  }
  - int32_t index() const {
  + uint32_t index() const {
  if constexpr (is_jit_array_v<Type>)
  return m_value.index();
  else
  