FIX: Endless spinner when anonymous users navigated to 404s

test/javascripts/acceptance/topic-anonymous-test.js.es6

@@ -16,6 +16,14 @@ test("Enter without an id", () => {
   });
 });
 
+test("Enter a 404 topic", (assert) => {
+  visit("/t/not-found/404");
+  andThen(() => {
+    assert.ok(!exists("#topic"), "The topic was not rendered");
+    assert.ok(find(".not-found").text() === "not found", "it renders the error message");
+  });
+});
+
 test("Enter without access", (assert) => {
   visit("/t/i-dont-have-access/403");
   andThen(() => {

test/javascripts/helpers/create-pretender.js.es6

@@ -179,6 +179,10 @@ export default function() {
       return response(403, {});
     });
 
+    this.get('/t/404.json', () => {
+      return response(404, "not found");
+    });
+
     this.get('/t/500.json', () => {
       return response(502, {});
     });