message: Fix material crash.
diff: @@ -1785,11 +1785,7 @@ void forEachPrimitiveComponent(UCesiumGltfComponent* pGltf, Func&& f) {
  UMaterialInstanceDynamic* pMaterial =
  Cast<UMaterialInstanceDynamic>(pPrimitive->GetMaterial(0));
  -#if ENGINE_MAJOR_VERSION >= 5
  - if (!IsValid(pMaterial)) {
  -#else
  - if (pMaterial->IsPendingKillOrUnreachable()) {
  -#endif
  + if (!IsValid(pMaterial) || pMaterial->IsUnreachable()) {
  // Don't try to update the material while it's in the process of being
  // destroyed. This can lead to the render thread freaking out when
  // it's asked to update a parameter for a material that has been
  