Weird error to do with app_namespace

[cogat]

Steps to reproduce (using acmi 00dc06e69364 and icekit 18ea0d8 - it should be possible to reproduce by reinstating the {% extends %} block in the ACMI contact_person template):

1. Preview a fluent page that contains a File
2. On local, you'll get a console error (it can't render the technical 500 page) TypeError: coercing to Unicode: need string or buffer, NamespaceOrigin found, On staging you get https://sentry.ixcsandbox.com/ic/acmi-stg/group/5714/

NB that the path to the template is namespaced, and is a result of the template at templates/icekit/plugins/contact_person/default.html calling {% extends "icekit_plugins_contact_person:icekit/plugins/contact_person/default.html" %}

Amusingly, this template should be nothing to do with the File content plugin - though the file template is namespaced the same way.

For now, I'll workaround by removing the {% extends %} override.

[cogat]

Turns out the file template was incorrectly extending "icekit_plugins_contact_person:icekit/plugins/contact_person/default.html" I assume the error is some sort of namespace violation.