Added Debuggify.

js_error_tracker.py

from random import shuffle

debuggify = '''
<script type="text/javaScript" src="https://cdn.debuggify.net/js/a4f458fc1c74cf2b60f0909da8531164/debuggify.logger.http.js"></script>
'''

qbaka = '''
<script type="text/javascript">
(function(a,c){a.__qbaka_eh=a.onerror;a.__qbaka_reports=[];a.onerror=function(){a.__qbaka_reports.push(arguments);if(a.__qbaka_eh)try{a.__qbaka_eh.apply(a,arguments)}catch(b){}};a.onerror.qbaka=1;a.qbaka={report:function(){a.__qbaka_reports.push([arguments, new Error()]);},customParams:{},set:function(a,b){qbaka.customParams[a]=b},exec:function(a){try{a()}catch(b){qbaka.reportException(b)}},reportException:function(){}};var b=c.createElement("script"),e=c.getElementsByTagName("script")[0],d=function(){e.parentNode.insertBefore(b,e)};b.type="text/javascript";b.async=!0;b.src="//cdn.qbaka.net/reporting.js";"[object Opera]"==a.opera?c.addEventListener("DOMContentLoaded",d):d();qbaka.key="a72f5cc63c961ae53e177e4ca071beb5"})(window,document);qbaka.options={autoStacktrace:1,trackEvents:1};
</script>
'''

errorception = '''
<script>
    (function(_,e,rr,s){_errs=[s];var c=_.onerror;_.onerror=function(){var a=arguments;_errs.push(a);
    c&&c.apply(this,a)};var b=function(){var c=e.createElement(rr),b=e.getElementsByTagName(rr)[0];
    c.src="//beacon.errorception.com/"+s+".js";c.async=!0;b.parentNode.insertBefore(c,b)};
    _.addEventListener?_.addEventListener("load",b,!1):_.attachEvent("onload",b)})
    (window,document,"script","51f15fe26c7008af50000013");
</script>
'''

exceptional = '''
<script type="text/javascript" src="http://js.exceptional.io/exceptional.js"></script>
<script type="text/javascript">
  Exceptional.setKey('15fee4c8997d080bd8fcf93391bdee181f6f8133');
</script>
'''

js_error_tracker = [debuggify, qbaka, errorception, exceptional]
shuffle(js_error_tracker)
js_error_tracker = js_error_tracker[0]

I'll implement this on mainpage.html and create a PR