InigoValentin/app/views/contact/error.erb

{
    "response": {
        "status": "ERROR",
        "errors": [
            <%
                i = 0
                max = @errors.length
                @errors.each do |error|
            %>
                    "<%= error %>"
                    <% if (i + 1) < max %>
                        ,
                    <% end %>
                    <% i = i + 1 %>
            <% end %>
        ]
    }
}