nl_tokens: Constructs an InvalidSlugError .
pl_tokens: function InvalidSlugError ( <mask> ) { if ( ! ( this instanceof InvalidSlugError ) ) { return new InvalidSlugError ( message ) ; } Error . captureStackTrace ( this , InvalidSlugError ) ; // Like http://www.ecma-international.org/ecma-262/6.0/#sec-error-message if ( message !== undefined ) { Object . defineProperty ( this , 'message' , { value : String ( message ) , configurable : true , writable : true } ) ; } }