Add web front-end and fix API issues

node_modules/rxjs/dist/cjs/internal/operators/defaultIfEmpty.js

@@ -0,0 +1,21 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.defaultIfEmpty = void 0;
+var lift_1 = require("../util/lift");
+var OperatorSubscriber_1 = require("./OperatorSubscriber");
+function defaultIfEmpty(defaultValue) {
+    return lift_1.operate(function (source, subscriber) {
+        var hasValue = false;
+        source.subscribe(OperatorSubscriber_1.createOperatorSubscriber(subscriber, function (value) {
+            hasValue = true;
+            subscriber.next(value);
+        }, function () {
+            if (!hasValue) {
+                subscriber.next(defaultValue);
+            }
+            subscriber.complete();
+        }));
+    });
+}
+exports.defaultIfEmpty = defaultIfEmpty;
+//# sourceMappingURL=defaultIfEmpty.js.map