function done( error, bundle ) {
		debug( 'Deleting temporary file...' );
		rmfile( tmpfile, onDelete );
		if ( error ) {
			return cb( error );
		}
		debug( 'Finished.' );
		if ( bundle ) {
			return cb( null, bundle );
		}
		cb();
	}
Callback invoked upon completion.

@private
@param {(Error|null)} [error] - error object
@param {(string|Buffer)} [bundle] - bundle
@returns {void}