Problem using jinja in custom panel

Development
1

I wrote a costum panel and set it up with:

- name: hello
  sidebar_title: Hello World
  sidebar_icon: mdi:hand-pointing-right
  url_path: hello

and here is my costum template:

<dom-module id='ha-panel-hello'>
  <template>
    <style include="ha-style"></style>
    <app-toolbar>
      <ha-menu-button narrow="[[narrow]]" show-menu="[[showMenu]]"></ha-menu-button>
      <div main-title="">[[panel.title]]</div>
    </app-toolbar>

    <p>Hello {{ states("camera.cam") }}</p>

  </template>
</dom-module>

<script>
Polymer({
    is: "ha-panel-hello",
    properties: {
        panel: {
            type: Object
        },
        narrow: {
            type: Boolean
        },
        showMenu: {
            type: Boolean
        }
    }
})
</script>

The problem is where it should print the state, it just prints an empty space. It seems like an issue with jinja, when i tried {{ 1+1 }} it just displayed the text. These examples work in dev-template panel.

Also a question. Why are the html sources in homeassistant/components/frontend/ minified? How can I beautify them?