message: Minor MaterialDisposal Fix.
diff: @@ -683,7 +683,11 @@ export class Tile implements CachedResource {
  if (object.material !== undefined && this.shouldDisposeObjectMaterial(object)) {
  if (object.material instanceof Array) {
  - object.material.forEach(material => material.dispose());
  + object.material.forEach(material => {
  + if (material !== undefined) {
  + material.dispose();
  + }
  + });
  } else {
  object.material.dispose();
  }
  