feat(tests): add test coverage for index.js

ui/src/index.js

@@ -16,7 +16,9 @@ SetupRaven(settingsElement);
 Moment.startPooledTimer();
 
 const defaultFilters = ParseDefaultFilters(settingsElement);
-ReactDOM.render(
+
+// https://wetainment.com/testing-indexjs/
+export default ReactDOM.render(
   <App defaultFilters={defaultFilters} />,
-  document.getElementById("root")
+  document.getElementById("root") || document.createElement("div")
 );

ui/src/index.test.js

@@ -0,0 +1,5 @@
+import Index from "./index.js";
+
+it("renders without crashing", () => {
+  expect(Index).toBeTruthy();
+});