message: fix gather compilation error when mask is an Array<CUDAArray<>>
diff: @@ -13,7 +13,8 @@ ENOKI_INLINE Array gather(const Source &source, const Index &index,
  const identity_t<Mask> &mask = true) {
  if constexpr (array_depth_v<Source> == 1) {
  - if constexpr (is_dynamic_v<Array> && is_dynamic_v<Source>) {
  + if constexpr (is_dynamic_v<Array> && is_dynamic_v<Source> &&
  + array_depth_v<Source> >= array_depth_v<Mask>) {
  if (source.size() <= 1)
  return source & mask;
  }
  