Fix error message when clicking on unhealthy app

Fixes cloudron/box#643

src/js/index.js

@@ -207,6 +207,11 @@ app.filter('activeOAuthClients', function () {
 // this appears when an item in app grid is clicked
 app.filter('prettyAppMessage', function () {
     return function (app) {
+        if (app.installationState === ISTATES.INSTALLED) {
+            // app.health can also be null to indicate insufficient data
+            if (app.health === HSTATES.UNHEALTHY) return 'The app is not responding to health checks. Check the logs for any error messages.';
+        }
+
         var message = app.message;
         if (message === 'ETRYAGAIN') return 'The DNS record for this location is not setup correctly. Please verify your DNS settings and repair this app.';
         if (message === 'DNS Record already exists') return 'The DNS record for this location already exists. Cloudron does not remove existing DNS records. Manually remove the DNS record and then click on repair.';