message: test(typeguards): remove "as Class" casts where possible
diff: import { assertion, isNullOrUndefined } from '../../src/internal/utils';
  import { isDocument, isDocumentArray, isRefType, isRefTypeArray, mongoose } from '../../src/typegoose';
  import {
  - IsRefType,
  IsRefTypeArrayModel,
  IsRefTypeModel,
  IsRefTypeNestedObjectIdModel,
  @@ -168,7 +167,8 @@ describe('isRefType / isRefTypeArray', () => {
  it('should guarantee the RefType - String', async () => {
  const doc = await IsRefTypeModel.create({
  nestedString: await IsRefTypeNestedStringModel.create({ _id: 'should guarantee the RefType' }),
  - } as IsRefType);
  + });
  +
  doc.depopulate('nestedString');
  expect(doc.nestedString).not.toBeUndefined();
  @@ -183,7 +183,8 @@ describe('isRefType / isRefTypeArray', () => {
  it('should guarantee the RefType - ObjectId', async () => {
  const doc = await IsRefTypeModel.create({
  nestedObjectId: await IsRefTypeNestedObjectIdModel.create({ _id: new mongoose.Types.ObjectId() }),
  - } as IsRefType);
  + });
  +
  doc.depopulate('nestedObjectId');
  expect(doc.nestedObjectId).not.toBeUndefined();
  