cope with bad icons in the json (bug 741980)

apps/devhub/tests/addons/badicon.webapp

@@ -0,0 +1,6 @@
+{
+    "version": "1.0",
+    "name": "MozillaBall",
+    "description": "Exciting Open Web development action!",
+    "icons": {'asd'},
+}

mkt/developers/tasks.py

@@ -331,7 +331,12 @@ def fetch_icon(webapp, **kw):
         # Set the icon type to empty.
         webapp.update(icon_type='')
         return
-    biggest = max([int(size) for size in manifest['icons']])
+
+    try:
+        biggest = max([int(size) for size in manifest['icons']])
+    except ValueError:
+        return
+
     icon_url = manifest['icons'][str(biggest)]
     if icon_url.startswith('data:image'):
         image_string = icon_url.split('base64,')[1]

mkt/developers/tests/addons/badicon.webapp

@@ -0,0 +1,6 @@
+{
+    "version": "1.0",
+    "name": "MozillaBall",
+    "description": "Exciting Open Web development action!",
+    "icons": {'asd'},
+}

mkt/developers/tests/test_tasks.py

@@ -290,6 +290,12 @@ class TestFetchIcon(BaseWebAppTest):
         tasks.fetch_icon(iconless_app)
         assert not self.urlopen_mock.called
 
+    def test_bad_icons(self):
+        path = os.path.join(self.apps_path, 'badicon.webapp')
+        iconless_app = self.webapp_from_path(path)
+        tasks.fetch_icon(iconless_app)
+        assert not self.urlopen_mock.called
+
     def check_icons(self, webapp):
         manifest = webapp.get_manifest_json()
         biggest = max([int(size) for size in manifest['icons']])