Consider handling errors with detailed API responses

[abdullah]

Problem Description

When the Gotenberg API fails, it provides valuable error details in the response body that explain the failure reason. Currently, in https://github.com/cherfia/chromiumly/blob/main/src/common/gotenberg.utils.ts, the fetch method discards these details and only throws the HTTP status code and status text, making production debugging difficult. For example, the current error output is limited to:

400 Bad Request

or

503 Service Unavailable 

However, Gotenberg includes specific error details in the response body. By modifying the fetch method to capture and include these details, we can better understand why requests fail. Below is the improved implementation (for our use case).

Our patch version for reference

import { GotenbergError } from '#/exceptions/error';
import { GotenbergUtils } from 'chromiumly/dist/common';

GotenbergUtils.fetch = async function (
  endpoint: string,
  data: FormData,
  username?: string,
  password?: string,
  customHttpHeaders?: Record<string, string>
): Promise<Buffer> {
  console.log('fetch', endpoint, data, username, password, customHttpHeaders);

  const headers: Record<string, string> = { ...customHttpHeaders };

  if (username && password) {
    const authHeader = 'Basic ' + Buffer.from(username + ':' + password).toString('base64');
    headers.Authorization = authHeader;
  }

  const response = await fetch(endpoint, {
    method: 'POST',
    body: data,
    headers
  });

  if (!response.ok) {
    let message = await response.text().catch(() => response.statusText);

    if (response.status === 503) {
      message = 'Your request is taking longer than expected or the generated file is too large.';
    }

    throw new GotenbergError(message, response.status);
  }

  const arrayBuffer = await response.arrayBuffer();

  return Buffer.from(arrayBuffer);
};

export class GotenbergError extends Error {
  statusCode: number;

  constructor(message: string | undefined, statusCode: number) {
    super(message);
    this.statusCode = statusCode;
  }
}

[cherfia]

@abdullah Thanks a lot for reporting this and for your suggestions. The next release will have more detailed error messages 👍