Handle 404s for agents

ui/app/routes/servers/server.js

@@ -0,0 +1,10 @@
+import Ember from 'ember';
+import notifyError from 'nomad-ui/utils/notify-error';
+
+const { Route } = Ember;
+
+export default Route.extend({
+  model() {
+    return this._super(...arguments).catch(notifyError(this));
+  },
+});

ui/app/serializers/agent.js

@@ -1,4 +1,5 @@
 import ApplicationSerializer from './application';
+import { AdapterError } from 'ember-data/adapters/errors';
 
 export default ApplicationSerializer.extend({
   attrs: {
@@ -8,6 +9,16 @@ export default ApplicationSerializer.extend({
   },
 
   normalize(typeHash, hash) {
+    if (!hash) {
+      // It's unusual to throw an adapter error from a serializer,
+      // but there is no single server end point so the serializer
+      // acts like the API in this case.
+      const error = new AdapterError([{ status: '404' }]);
+
+      error.message = 'Requested Agent was not found in set of available Agents';
+      throw error;
+    }
+
     hash.ID = hash.Name;
     hash.Datacenter = hash.Tags && hash.Tags.dc;
     hash.Region = hash.Tags && hash.Tags.region;