Add web front-end and fix API issues

node_modules/yargs/build/lib/utils/maybe-async-result.js

@@ -0,0 +1,17 @@
+import { isPromise } from './is-promise.js';
+export function maybeAsyncResult(getResult, resultHandler, errorHandler = (err) => {
+    throw err;
+}) {
+    try {
+        const result = isFunction(getResult) ? getResult() : getResult;
+        return isPromise(result)
+            ? result.then((result) => resultHandler(result))
+            : resultHandler(result);
+    }
+    catch (err) {
+        return errorHandler(err);
+    }
+}
+function isFunction(arg) {
+    return typeof arg === 'function';
+}