How to override the error serializer?

[punkpeye]

Problem Statement

The problem is that I am throwing an error with custom properties, e.g.

export class UnexpectedStateError extends Error {
  public cause?: unknown;

  public extra?: Extras;

  public constructor(
    message: string,
    options?: { cause?: unknown; extra?: Extras },
  ) {
    super(message);

    this.name = new.target.name;
    this.extra = options?.extra;
    this.cause = options?.cause;
  }
}

throw new UnexpectedStateError('foo', {
  extra: {
    mcpServerId,
  },
});

Now, the earliest that I am able to catch the error appears to be here:

Sentry.addEventProcessor(async (event) => {
  console.log('[instrument] Sentry.addEventProcessor', event);

  return event;
});

but at this point, I already cannot find my extra property anymore.

Solution Brainstorm

• allow to customize the serializer for erros
• update the serializer to always capture the contents of extra property (aligns with captureException)

[linear]

JS-775 How to override the error serializer?

[punkpeye]

I should note that I already have extraErrorDataIntegration integration enabled.

Sentry.extraErrorDataIntegration({
  captureErrorCause: true,
  depth: 5,
});

[punkpeye]

or maybe it would be cool if something like this would be possible:

lass UnexpectedStateError extends Error {
  public cause?: unknown;

  public extra?: Extras;

  public constructor(
    message: string,
    options?: { cause?: unknown; extra?: Extras },
  ) {
    super(message);

    console.warn(`UnexpectedStateError: ${message}`, {
      cause: options?.cause,
      extra: options?.extra,
    });

    this.name = new.target.name;
    this.extra = options?.extra;
    this.cause = options?.cause;

    const extra = options?.extra;

    if (extra) {
      // Would want this to be captured by Sentry, but it seems like it might be too late to add it to the scope.
      withScope((scope) => {
        for (const [key, value] of Object.entries(extra)) {
          scope.setExtra(key, value);
        }
      });
    }
  }
}

[timfish]

There's an optional second parameter of EventHint:

Sentry.addEventProcessor(async (event, hint) => {
  console.log('[instrument] Sentry.addEventProcessor', event, hint);

  return event;
});

This has as originalException property which should be the original error. Here you can check hint.originalException instanceof UnexpectedStateError and then do whatever you want with the error properties.