function errorListener( error ) {
			if ( error.code === 'EADDRINUSE' ) {
				debug( 'Server address already in use: %s:%d.', hostname, port );
				port += 1;
				if ( port <= max ) {
					debug( 'Attempting to listen on %s:%d.', hostname, port );
					server.listen( port, hostname );
					return;
				}
			}
			throw error;
		}
Server error event handler.

@private
@param {Error} error - server error
@throws {Error} server error