Cannot read property 'value' of undefined

[nova76]

I received this error messages, while simple use: Cannot read property 'value' of undefined

http://plnkr.co/edit/xjgiRk9RdcgBdRAFtCM3?p=preview

Interestingly, if you reversed the order of the two javascript , it works in spite of the error

from:

    <script src="http://ignitersworld.com/lab/assets/js/radialIndicator.js?32"></script>
    <script src="script.js"></script>

To:

    <script src="script.js"></script>
    <script src="http://ignitersworld.com/lab/assets/js/radialIndicator.js?32"></script>