not able to start "node app.js"

[sachinbanugariya]

we use elgg 1.11,
getting below error when try to start app.js

/usr/local/nginx/html/elgg/mod/elgg-nodejs/node/app.js:153
return socket.handshake.headers.cookie.match(/Elgg=(\S*);?/)[1];
^
TypeError: Cannot read property '1' of null
at getElggSession (/usr/local/nginx/html/elgg/mod/elgg-nodejs/node/app.js:153:62)
at Namespace. (/usr/local/nginx/html/elgg/mod/elgg-nodejs/node/socket.js:20:20)
at Namespace.emit (events.js:117:20)
at Namespace.emit (/usr/local/nginx/html/elgg/mod/elgg-nodejs/node/node_modules/socket.io/lib/namespace.js:209:10)
at /usr/local/nginx/html/elgg/mod/elgg-nodejs/node/node_modules/socket.io/lib/namespace.js:176:14
at process._tickCallback (node.js:458:13)