message: Fix sampler extraction for old models.
diff: @@ -726,7 +726,7 @@ export namespace GltfTileIO {
  if (undefined === textureJson)
  return Promise.resolve();
  - return this.loadTextureImage(this.images[textureJson.source], this.samplers[textureJson.sampler]).then((texture) => {
  + return this.loadTextureImage(this.images[textureJson.source], undefined === this.samplers ? undefined : this.samplers[textureJson.sampler]).then((texture) => {
  textureJson.renderTexture = texture;
  });
  }
  