Add web front-end and fix API issues

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

@@ -0,0 +1,11 @@
+import { createErrorClass } from './createErrorClass';
+export const UnsubscriptionError = createErrorClass((_super) => function UnsubscriptionErrorImpl(errors) {
+    _super(this);
+    this.message = errors
+        ? `${errors.length} errors occurred during unsubscription:
+${errors.map((err, i) => `${i + 1}) ${err.toString()}`).join('\n  ')}`
+        : '';
+    this.name = 'UnsubscriptionError';
+    this.errors = errors;
+});
+//# sourceMappingURL=UnsubscriptionError.js.map