src/vs/workbench/api/browser/mainThreadNotebook.ts/MainThreadNotebooks/$unregisterNotebookProvider
class MainThreadNotebooks:	async $unregisterNotebookProvider(viewType: string): Promise<void> {
		const entry = this._notebookProviders.get(viewType);
		if (entry) {
			entry.disposable.dispose();
			this._notebookProviders.delete(viewType);
		}
	}