index.js
function addOption(optName, optDefault) {
  if (typeof optDefault !== 'function') {
    const val = optDefault;
    optDefault = () => val;
  }
  customOptions[optName] = optDefault;
}
function addOption(optName, optDefault) {
  if (typeof optDefault !== 'function') {
    const val = optDefault;
    optDefault = () => val;
  }
  customOptions[optName] = optDefault;
}
function addOption ( optName , optDefault ) { if ( typeof optDefault !== 'function' ) { const val = optDefault ; optDefault = ( ) => val ; } customOptions [ optName ] = optDefault ; }
Adds custom options to errors' body.
@param  {string} optName Name of the option key to add.
@param  {}       [optDefault] Default value for the option.
If a function is provided it will be called with
(errorCode, errorHttpCode, errorMessage) as parameters.
You can use this behaviour to provide different default for each error.
Adds custom options to errors body .