Add web front-end and fix API issues

node_modules/rxjs/dist/esm/internal/util/isObservable.js

@@ -0,0 +1,6 @@
+import { Observable } from '../Observable';
+import { isFunction } from './isFunction';
+export function isObservable(obj) {
+    return !!obj && (obj instanceof Observable || (isFunction(obj.lift) && isFunction(obj.subscribe)));
+}
+//# sourceMappingURL=isObservable.js.map