code: function prepareStackTraceError(err, structuredStackTrace) {
    var returnObj = new CustomStackTrace();
    var topFrame = {};
  
    if (!Array.isArray(structuredStackTrace)) {
  
      return returnObj;
    }
    // Get the topframe of the CallSite array
    topFrame = structuredStackTrace[0];
  
    returnObj.setFilePath(topFrame.getFileName())
        .setLineNumber(topFrame.getLineNumber())
        .setFunctionName(topFrame.getFunctionName())
        .setStringifyStructuredCallList(
            extractStructuredCallList(structuredStackTrace));
  
    return returnObj;
  }
docs: A function which is built to override the Error.prepareStackTraceError
  builtin formatter. This substitution produces a object with the last frames
  file-path, line number and function name. Additionally a fourth property,
  named stringifyStucturedCallList contains a function which can produce the
  entirety of the stack trace in JSON form when called.
  @function prepareStackTraceError
  @param {Error} err - an instantiation of the Error class
  @param {Array<CallSite>} structuredStackTrace - an array of CallSite objects
  @returns {CustomStackTrace} - A custom stack trace instance