Snippers for better error handling in Typescript

better-error.ts

/**
 * Base error class that all application errors should extend.
 *
 * Like the native `Error`, but ensures subclasses are properly initialised and correctly typed.
 */
export class BaseError extends Error {
  constructor(message: string) {
    super(message);
    Object.defineProperty(this, "name", { value: new.target.name });
    Object.setPrototypeOf(this, new.target.prototype);
  }

  /**
   * Adds a 'cause' for this error
   */
  from(cause: unknown): ExtError {
    this.cause = cause;
    return this;
  }
}

type Constructor<T> = { new (...args: any[]): T };
type ArrayType<T extends unknown[]> = T extends (infer U)[] ? U : never;

/**
 * Returns true if the given error matches any of the given error types.
 *
 * @returns true if the given error is an instanceof one of the given error types, false otherwise
 *
 * @example
 * ```
 *  try {
 *    // ...
 *  } catch (err) {
 *    if (matchErr(err, MyApplicationError)) {
 *      console.log('Application failed in an expected way!');
 *    }
 *  }
 * ```
 */
export function matchErr<T extends Constructor<Error>[]>(
  error: unknown,
  ...types: T
): error is InstanceType<ArrayType<T>> {
  return types.some((type) => error instanceof type);
}

/**
 * Returns true if the given `error` matches any of the given error `types`.
 *
 * @returns true if the given error's type matched one of the given error types
 * @throws error if its type didnt match the given error types
 *
 * @example
 * ```
 *  try {
 *    // ...
 *  } catch (err) {
 *    if (matchErrOrThrow(err, MyApplicationError)) {
 *      console.log('Application failed in an expected way!');
 *    }
 *  }
 * ```
 */
export function matchErrOrThrow<T extends Constructor<Error>[]>(
  error: unknown,
  ...types: T
): error is InstanceType<ArrayType<T>> {
  if (matchErr(error, ...types)) {
    return true;
  } else {
    throw error;
  }
}