Some sanity checks that prevent crash while documenting my code.

I have a farily large javascript codebase, but the template failed to build the documentation tossing the following error:

<pre>
undefined:7
if (data.description) {
        ^
TypeError: Cannot read property 'description' of undefined
    at eval (eval at <anonymous> (/usr/local/lib/node_modules/jsdoc/node_modules/underscore/underscore.js:1156:16), <anonymous>:7:9)
    at template (/usr/local/lib/node_modules/jsdoc/node_modules/underscore/underscore.js:1164:21)
...
</pre>

I have just made some sanity checks in the template code, avoiding potential undefined data.
Now it works for me and can have a decent documentation.