index.js
function( error ) {
		if( error instanceof Buffer && error.toString().match( app.options.errorMessage ) ) {
			initialized( 'Development server has error.' );
		}
	}
function( error ) {
		if( error instanceof Buffer && error.toString().match( app.options.errorMessage ) ) {
			initialized( 'Development server has error.' );
		}
	}
function ( error ) { if ( error instanceof Buffer && error . toString ( ) . match ( app . options . errorMessage ) ) { initialized ( 'Development server has error.' ) ; } }
initialized by `errorMessage` if server printed error
initialized by errorMessage if server printed error