Fixing tags property

Hi,

jsctags was not working on my system, 

 Array.prototype.push called on null or undefined
 
  /usr/local/bin/jsctags:195
                  throw e;
                        ^
  TypeError: Array.prototype.push called on null or undefined
    at Object.exports.Tags.Object.create.Trait.compose.Trait.add (/usr/local/lib/jsctags/ctags/index.js:72:30)
    at Object.exports.Tags.Object.create.Trait.compose.Trait.scan (/usr/local/lib/jsctags/ctags/index.js:106:14)
    at processPath (/usr/local/bin/jsctags:189:18)
    at /usr/local/bin/jsctags:184:13
    at Array.forEach (native)
    at processPath (/usr/local/bin/jsctags:183:27)
    at /usr/local/bin/jsctags:184:13
    at Array.forEach (native)
    at processPath (/usr/local/bin/jsctags:183:27)
    at Object.<anonymous> (/usr/local/bin/jsctags:207:5)

this patch seems to fix it