Add web front-end and fix API issues

node_modules/rxjs/dist/esm/internal/operators/isEmpty.js

@@ -0,0 +1,14 @@
+import { operate } from '../util/lift';
+import { createOperatorSubscriber } from './OperatorSubscriber';
+export function isEmpty() {
+    return operate((source, subscriber) => {
+        source.subscribe(createOperatorSubscriber(subscriber, () => {
+            subscriber.next(false);
+            subscriber.complete();
+        }, () => {
+            subscriber.next(true);
+            subscriber.complete();
+        }));
+    });
+}
+//# sourceMappingURL=isEmpty.js.map