"Coroutine parameter must be passed by value for safe access" how can I do it? - c++-winrt

Question

I made a C++/WinRT module which implements Windows.Storage.Pickers.FileOpenPicker and FileSavePicker to React Native for Windows. This is my FilePicker.h:
#pragma once
#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.Storage.h>
#include <winrt/Windows.Storage.Pickers.h>
#include "pch.h"
#include "JSValue.h"
#include "NativeModules.h"
using namespace std;
using namespace winrt;
using namespace winrt::Microsoft::ReactNative;
using namespace Windows::Foundation;
using namespace Windows::Storage;
using namespace Windows::Storage::Pickers;
using namespace Windows::UI::Xaml;
namespace FilePicker
{
REACT_MODULE(Panel);
struct Panel
{
REACT_METHOD(Open, L"open");
fire_and_forget Open(wchar_t ext[], React::ReactPromise<string> promise) noexcept
{
wchar_t str[32] = L".";
wcscat_s(str, 32, ext);
FileOpenPicker openPicker;
openPicker.ViewMode(PickerViewMode::List);
openPicker.SuggestedStartLocation(PickerLocationId::DocumentsLibrary);
openPicker.FileTypeFilter().ReplaceAll({ str });
StorageFile file = co_await openPicker.PickSingleFileAsync();
if (file == nullptr) {
promise.Reject("No file selected.");
} else {
promise.Resolve(to_string(file.Path()));
}
}
REACT_METHOD(Save, L"save");
fire_and_forget Save(wchar_t ext[], wchar_t content[]) noexcept
{
wchar_t str[32] = L".";
wcscat_s(str, 32, ext);
FileSavePicker savePicker;
savePicker.SuggestedStartLocation(PickerLocationId::DocumentsLibrary);
savePicker.FileTypeChoices().Insert(L"", single_threaded_vector<hstring>({ str }));
StorageFile file = co_await savePicker.PickSaveFileAsync();
await FileIO::WriteTextAsync(file, content);
}
};
}
and I linked it to testing RNW project, which App.tsx is this:
import React from 'react';
import { Button, Text, View } from 'react-native';
import { open, save } from 'react-native-file-panel';
export default class App extends React.Component<undefined, { text: string }> {
constructor(props: undefined) {
super(props);
this.state = { text: '' };
}
render() {
return (
<View>
<Button title='SAVE' onPress={ () => save('txt', 'The quick fox jumps over the lazy dog.') } />
<Button title='OPEN' onPress={ () => open('txt').then((content: string) => this.setState({ text: content })) } />
<Text>{ this.state.text }</Text>
</View>
);
}
}
But when I ran it, this error occurs:
error C2338: Coroutine parameter must be passed by value for safe access: void __cdecl winrt::Microsoft::ReactNative::ValidateCoroutineArg<struct winrt::fire_and_forget,wchar_t*>(void) noexcept
I tried to modify, and googled, nothing was helped.
Anyone knows the solution?