TypeError at app details page

[groovecoder]

http://dev-dashboard.deis.dev.mozaws.net/en/push/apps/32/

Environment:

Request Method: GET
Request URL: http://dev-dashboard.deis.dev.mozaws.net/en/push/apps/32/

Django Version: 1.9.5
Python Version: 2.7.11
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'allauth',
 'allauth.account',
 'allauth.socialaccount',
 'django_extensions',
 'pipeline',
 'rest_framework',
 'rest_framework_swagger',
 'waffle',
 'dashboard',
 'dashboard.socialaccount.providers.fxa',
 'domains',
 'push']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'csp.middleware.CSPMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'waffle.middleware.WaffleMiddleware']

Traceback:

File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/contrib/auth/mixins.py" in dispatch
  116.         return super(UserPassesTestMixin, self).dispatch(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/newrelic-2.64.0.48/newrelic/hooks/framework_django.py" in wrapper
  831.             return wrapped(*args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py" in get
  157.         context = self.get_context_data(**kwargs)

File "/usr/src/app/push/views.py" in get_context_data
  74.         context.update({'app_messages': app_messages['messages']})

Exception Type: TypeError at /en/push/apps/32/
Exception Value: 'NoneType' object has no attribute '__getitem__'