function constructErrorMessage (ajvError) {
  let message = 'Provided API Specification is invalid. ';

  message += ajvError.message;

  if (ajvError.params) {
    message += ' ' + JSON.stringify(ajvError.params);
  }

  if (typeof ajvError.instancePath === 'string') {
    message += ` at "${jsonPointerDecodeAndReplace(ajvError.instancePath)}"`;
  }

  return message;
}
Constructs Error message from given AJV Validation Error object.

@param {Object} ajvError - AJV Validation Error object (reference: https://ajv.js.org/#validation-errors)
@returns {String} - Error message constructed (To be displayed as error message for invalid specs)