message: fix: DuckDbError should be an interface
diff: * See https://duckdb.org/docs/api/nodejs/overview for details
  * on Node.JS API
  */
  -export class DuckDbError extends Error {
  - errno: number;
  - code: string;
  +
  +/**
  + * Standard error shape for DuckDB errors
  + */
  +export interface DuckDbError extends Error {
  + errno: -1; // value of ERROR
  + code: 'DUCKDB_NODEJS_ERROR';
  }
  type Callback<T> = (err: DuckDbError | null, res: T) => void;
  