import { Observable } from 'rxjs';
/**
 * Creates an IDBDatabase by upgrading the database version.
 * This allows us to create ObjectStores on this database instance.
 *
 * @remarks This should only be used internally, that is why it is not exported in the index.ts file
 *
 * @throws Error when the database that is supposed to be upgraded does not exist.
 *
 * @param existingDb - An existing IDBDatabase instance
 * @returns An Observable that emits a version update IDBDatabase instance
 */
export declare function upgradeDatabase(existingDb: IDBDatabase): Observable<IDBDatabase>;