Non-admins do not have a checklist property, so handle it correctly in AppsModel

dashboard/src/models/AppsModel.js

@@ -156,8 +156,13 @@ function create() {
       app.manifest.postInstallMessage = text.trim();
     }
 
-    for (const key of Object.keys(app.checklist)) {
-      app.checklist[key].message = expandTemplateVars(app.checklist[key].message);
+    // only admins have this property
+    if (app.checklist) {
+      for (const key of Object.keys(app.checklist)) {
+        app.checklist[key].message = expandTemplateVars(app.checklist[key].message);
+      }
+    } else {
+      app.checklist = {};
     }
 
     return app;