Fix for exception if label is not permitted

Fixes exception caused by combination of default_value and absence of
label in permitted labels

Change-Id: I9d45fcbfdc2520a34baab6ff435efec1f4e26b33

polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.js

@@ -66,7 +66,8 @@
     _getLabelValue(labels, permittedLabels, label) {
       if (label.value) {
         return label.value;
-      } else if (labels[label.name].hasOwnProperty('default_value')) {
+      } else if (labels[label.name].hasOwnProperty('default_value') &&
+                 permittedLabels.hasOwnProperty(label.name)) {
         // default_value is an int, convert it to string label, e.g. "+1".
         return permittedLabels[label.name].find(
             value => parseInt(value, 10) === labels[label.name].default_value);

polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row_test.html

@@ -281,5 +281,33 @@ limitations under the License.
       flushAsynchronousOperations();
       assert.strictEqual(element.selectedValue, '-1');
     });
+
+    test('default_value is null if not permitted', () => {
+      element.permittedLabels = {
+        Verified: [
+          '-1',
+          ' 0',
+          '+1',
+        ],
+      };
+      element.labels = {
+        'Code-Review': {
+          values: {
+            '0': 'No score',
+            '+1': 'good',
+            '+2': 'excellent',
+            '-1': 'bad',
+            '-2': 'terrible',
+          },
+          default_value: -1,
+        },
+      };
+      element.label = {
+        name: 'Code-Review',
+        value: null,
+      };
+      flushAsynchronousOperations();
+      assert.isNull(element.selectedValue);
+    });
   });
 </script>