Repository: axios/axios
File: lib/core/Axios.js (JavaScript)

Code before:
   * @param {?Object} config
   *
   * @returns {Promise} The Promise to be fulfilled
   */
  async request(configOrUrl, config) {
    try {
      return await this._request(configOrUrl, config);
    } catch (err) {
      if (err instanceof Error) {
        let dummy;

        Error.captureStackTrace ? Error.captureStackTrace(dummy = {}) : (dummy = new Error());

        // slice off the Error: ... line
        const stack = dummy.stack ? dummy.stack.replace(/^.+\n/, '') : '';

        if (!err.stack) {
          err.stack = stack;
          // match without the 2 top stack lines
        } else if (stack && !String(err.stack).endsWith(stack.replace(/^.+\n.+\n/, ''))) {
          try {
            err.stack += '\n' + stack
          } catch (e) {
            // ignore the case where "stack" is an un-writable property
          }
        }
      }

      throw err;
    }
  }

  _request(configOrUrl, config) {
    /*eslint no-param-reassign:0*/
    // Allow for axios('example/url'[, config]) a la fetch API
    if (typeof configOrUrl === 'string') {
      config = config || {};
      config.url = configOrUrl;
    } else {
      config = configOrUrl || {};
    }

    config = mergeConfig(this.defaults, config);

    const {transitional, paramsSerializer, headers} = config;

    if (transitional !== undefined) {
      validator.assertOptions(transitional, {
        silentJSONParsing: validators.transitional(validators.boolean),
        forcedJSONParsing: validators.transitional(validators.boolean),
        clarifyTimeoutError: validators.transitional(validators.boolean)

Review comment (bug):
Just in case, it would be better to wrap the entire condition, not just inside the else-if branch. It will fail if someone defines this prop as 
```
{
  get() {
    return null; // undefined // etc
  },
  set() {
    throw Error('read-only');
  }
}
```
This is just a potentially improbable case, but still.

Code after:
   * @param {?Object} config
   *
   * @returns {Promise} The Promise to be fulfilled
   */
  async request(configOrUrl, config) {
    try {
      return await this._request(configOrUrl, config);
    } catch (err) {
      if (err instanceof Error) {
        let dummy;

        Error.captureStackTrace ? Error.captureStackTrace(dummy = {}) : (dummy = new Error());

        // slice off the Error: ... line
        const stack = dummy.stack ? dummy.stack.replace(/^.+\n/, '') : '';
        try {
          if (!err.stack) {
            err.stack = stack;
            // match without the 2 top stack lines
          } else if (stack && !String(err.stack).endsWith(stack.replace(/^.+\n.+\n/, ''))) {
            err.stack += '\n' + stack
          }
        } catch (e) {
          // ignore the case where "stack" is an un-writable property
        }
      }

      throw err;
    }
  }

  _request(configOrUrl, config) {
    /*eslint no-param-reassign:0*/
    // Allow for axios('example/url'[, config]) a la fetch API
    if (typeof configOrUrl === 'string') {
      config = config || {};
      config.url = configOrUrl;
    } else {
      config = configOrUrl || {};
    }

    config = mergeConfig(this.defaults, config);

    const {transitional, paramsSerializer, headers} = config;

    if (transitional !== undefined) {
      validator.assertOptions(transitional, {
        silentJSONParsing: validators.transitional(validators.boolean),
        forcedJSONParsing: validators.transitional(validators.boolean),
        clarifyTimeoutError: validators.transitional(validators.boolean)
      }, false);