add(notification): request failure handler

Author: subinasr

app/src/views/AccountNotifications/EmailPreferences/SubscriptionModal/i18n.json

@@ -20,6 +20,7 @@
         "countriesSelectedLabel": "{numCountries} {countryLabel} selected",
         "countryLabelSingular": "country",
         "countryLabelPlural": "countries",
-        "unlimitedOptionValue": "Unlimited"
+        "unlimitedOptionValue": "No limit",
+        "detailFetchFailureMessage": "Failed to fetch subscription details"
     }
 }

app/src/views/AccountNotifications/EmailPreferences/SubscriptionModal/index.tsx

@@ -122,7 +122,12 @@ function SubscriptionModal(props: Props) {
                 }),
             );
         },
-        // TODO: handle failure
+        onFailure: () => {
+            alert.show(
+                strings.updateFailureMessage,
+                { variant: 'danger' },
+            );
+        },
     });
 
     const {