message: API Change: Element.getSubModel now returns Promise<Model>
diff: import { Code, CodeProps, GeometryStream, Placement3d, Placement2d } from "./IModel";
  import { assert } from "@bentley/bentleyjs-core/lib/Assert";
  -import { BentleyPromise } from "@bentley/bentleyjs-core/lib/Bentley";
  -import { DgnDbStatus } from "@bentley/imodeljs-dgnplatform/lib/DgnDb";
  import { ClassRegistry } from "./ClassRegistry";
  import { ElementAspect, ElementAspectProps, ElementMultiAspect, ElementUniqueAspect } from "./ElementAspect";
  import { JsonUtils } from "@bentley/bentleyjs-core/lib/JsonUtils";
  @@ -99,11 +97,11 @@ export class Element extends Entity implements EntityProps {
  }
  /** Get the Model that modeling this Element (if it exists). That is, the model that is beneath this element in the hierarchy. */
  - public async getSubModel(): BentleyPromise<DgnDbStatus, Model | undefined> {
  + public async getSubModel(): Promise<Model> {
  if (this.id.equals(this.iModel.elements.rootSubjectId))
  - return { result: undefined };
  + return Promise.reject(new Error("No subModel found"));
  - return this.iModel.models.getModel({ id: this.id });
  + return this.iModel.models.getModel(this.id);
  }
  /** Query for aspects rows (by aspect class name) associated with this element. */
  