Error running script : TypeError: Cannot read property '0' of null

Hello,

I am using a beaglebone Black Rev C

I am trying to run a simple program to make an led ON with a push button.But getting this error

/usr/local/lib/node_modules/bonescript/my.js:57
if(slot[0]) {
^
TypeError: Cannot read property ‘0’ of null
at Object.exports.load_dt (/usr/local/lib/node_modules/bonescript/my.js:57:20)
at Object.exports.create_dt (/usr/local/lib/node_modules/bonescript/my.js:123:33)
at Object.exports.setPinMode (/usr/local/lib/node_modules/bonescript/hw_capemgr.js:83:12)
at Object.f.pinMode (/usr/local/lib/node_modules/bonescript/index.js:160:15)
at Object. (/var/lib/cloud9/blinkled/readButton.js:7:3)
at Module._compile (module.js:456:26)
at Object.Module._extensions…js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.runMain [as _onTimeout] (module.js:497:10)

My code is…

var b = require(‘bonescript’);
var led = “P9_14”;
var button = “P8_11”;
b.pinMode(led, b.OUTPUT);
b.pinMode(button, b.INPUT);
var state = b.LOW;
b.digitalWrite(led, state);
b.attachInterrupt(button, true, b.CHANGE, toggle);
function toggle(x) {
if (x.value == b.HIGH) {
console.log(“The button is HIGH”);
b.digitalWrite(led, b.HIGH);
}
else {
console.log(“The button is LOW”);
b.digitalWrite(led, b.LOW);
}
}

I am getting this error by making the P9_14 an output…