APM Logonpage error web_host.js

I have an APM setup with SharePoint. I use a set of iRules. When I open an office document in chrome or firefow apm forms is triggered and the user is redirected to a mini IE browser. I always get this error on the logon page. Logonpage is customized but I tried with clean policy and an out of the bow loginpage, same error. Line 35 Script file path: public/include/js/web_host.js Path on disk : /var/sam/www/webtop/public/include/js/web_host.js

so line is this one:

DefaultExternalWebHostImpl.prototype.isAvailable = function() {
    line 35 here: return (window.external && typeof window.external === 'object');
}

Any ideas on why this is throwing the error?