Add web front-end and fix API issues

node_modules/rxjs/dist/esm/internal/observable/interval.js

@@ -0,0 +1,9 @@
+import { asyncScheduler } from '../scheduler/async';
+import { timer } from './timer';
+export function interval(period = 0, scheduler = asyncScheduler) {
+    if (period < 0) {
+        period = 0;
+    }
+    return timer(period, period, scheduler);
+}
+//# sourceMappingURL=interval.js.map