Looks like your syntax is incorrect
{% if(QueryString.GetValue("e_code") == null){""}else{ "<a href='http://someothersite.com?e-code="+QueryString.GetValue("e_code")+" class='btn btn-lg btn-icon-right'>" } |(identity)GlobalAdministrator%}
You're building a string so you need to either escape the double quotes or use single quotes.