fix TypeError for incompatible app categories on edit page (bug 708263)

apps/addons/forms.py

@@ -16,6 +16,7 @@ from access import acl
 import amo
 import captcha.fields
 from amo.fields import ColorField
+from amo.helpers import loc
 from amo.urlresolvers import reverse
 from amo.utils import slug_validator, slugify, sorted_groupby, remove_icons
 from addons.models import (Addon, AddonCategory, AddonUser, BlacklistedSlug,
@@ -231,7 +232,7 @@ class CategoryForm(forms.Form):
         max_cat = amo.MAX_CATEGORIES
         if getattr(self, 'disabled', False) and total:
             if categories[0].type == amo.ADDON_WEBAPP:
-                raise forms.ValidationError(_('Categories cannot be changed '
+                raise forms.ValidationError(loc('Categories cannot be changed '
                     'while your app is featured for this application.'))
             else:
                 raise forms.ValidationError(_('Categories cannot be changed '

apps/devhub/templates/devhub/addons/edit/basic.html

@@ -107,7 +107,7 @@
                   {% if form.disabled %}
                     <p class="addon-app-cats addon-app-cats-inline">
                       <b>{{ form.app.pretty }}:</b>
-                      {% set cats = dict(addon.app_categories).get(form.app) %}
+                      {% set cats = dict(addon.app_categories).get(form.app, []) %}
                       {{ cats|join(' &middot; ')|safe }}
                     </p>
                     <p>