message: Mark _registration as nullable
diff: @@ -9,7 +9,7 @@ import { IDisposable } from '../Disposable';
  export default class DefinitionMetadataDocumentProvider implements TextDocumentContentProvider, IDisposable {
  readonly scheme = "omnisharp-metadata";
  - private _registration: IDisposable;
  + private _registration?: IDisposable;
  private _documents: Map<string, MetadataResponse>;
  private _documentClosedSubscription: IDisposable;
  @@ -23,7 +23,7 @@ export default class DefinitionMetadataDocumentProvider implements TextDocumentC
  }
  public dispose(): void {
  - this._registration.dispose();
  + this._registration?.dispose();
  this._documentClosedSubscription.dispose();
  this._documents.clear();
  }
  @@ -48,7 +48,7 @@ export default class DefinitionMetadataDocumentProvider implements TextDocumentC
  this._registration = workspace.registerTextDocumentContentProvider(this.scheme, this);
  }
  - public provideTextDocumentContent(uri: Uri): string {
  + public provideTextDocumentContent(uri: Uri): string | undefined {
  return this._documents.get(uri.toString())?.Source;
  }
  