message: Get the morph target count from glTF
  glTF spec says that all primitives MUST have the same number of morph
  targets in the same order so these changes are more correct.
diff: @@ -444,7 +444,8 @@ void FAssetLoader::createRenderable(const cgltf_data* srcAsset, const cgltf_node
  Aabb aabb;
  - cgltf_size numMorphTargets = 0;
  + // glTF spec says that all primitives MUST have the same number of morph targets in the same order.
  + const cgltf_size numMorphTargets = mesh->weights_count;
  // For each prim, create a Filament VertexBuffer, IndexBuffer, and MaterialInstance.
  for (cgltf_size index = 0; index < nprims; ++index, ++outputPrim, ++inputPrim) {
  @@ -453,12 +454,11 @@ void FAssetLoader::createRenderable(const cgltf_data* srcAsset, const cgltf_node
  slog.e << "Unsupported primitive type in " << name << io::endl;
  }
  - if (inputPrim->targets_count > 0) {
  if (numMorphTargets > 0 && inputPrim->targets_count != numMorphTargets) {
  slog.e << "Sister primitives must all have the same number of morph targets."
  << io::endl;
  - }
  - numMorphTargets = inputPrim->targets_count;
  + mError = true;
  + continue;
  }
  // Create a material instance for this primitive or fetch one from the cache.
  