UIDispatcher how to return value/resolve/reject promise without crash? (Documentation unlcear)

Problem Description

I have two small native c++ modules which use the Launcher::LaunchFileAsync and FileOpenPicker::pickSingleFileAsync.

After upgrading from 0.63 to 0.65 we have to use the UIDispatcher in order for it to work. So I had a look at the following Documentation:
Using UIDispatcher with C++/WinRT

Unfortunately, the example lacks the bit about how to return a value from there (in that example, that would probably be the file.Path()).

So I digged a bit further and had a look at the following 4 modules inside react-native-windows:
Clipboard Module
AccessibilityInfoModule
ImageViewManagerModule
AlertModule

I tried multiple different variations now and had a look at the crash dump but I always crash with an Access Violation on the promise.resolve line.

What am I doing wrong there? I don't see a lot of differences between my code and the above modules despite the co_await usage.
I'm also having the same problem with FileOpenPicker where I'd want to resolve the tempFile.Path() after picking+moving it to the apps temp folder (StorageFile tempFile{ co_await file.CopyAsync(winrt::Windows::Storage::ApplicationData::Current().TemporaryFolder(), file.Name(), NameCollisionOption::ReplaceExisting) };)

Steps To Reproduce

1. Init a new project
2. Add the FileOpener posted below to the project
3. Add an openable file to the application folder (for example a pdf)
4. Call NativeModules.FileOpener.openFileAsync(filePath, shouldShowOpenWithDialog)

Expected Results

Not crash, resolve the promise to JS.

Documentation to reflect an actual usage of FileOpenPicker/UIDispatcher with result returns/promise.resolve.

CLI version

6.1.0

Environment

info Fetching system and libraries information...
System:
    OS: Windows 10 10.0.19043
    CPU: (12) x64 AMD Ryzen 5 5600X 6-Core Processor
    Memory: 24.72 GB / 31.94 GB
  Binaries:
    Node: 14.16.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.11 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 6.14.11 - C:\Program Files\nodejs\npm.CMD
    Watchman: Not Found
  SDKs:
    Android SDK:
      API Levels: 28, 29, 30
      Build Tools: 29.0.0, 29.0.1, 29.0.2, 29.0.3, 30.0.0, 30.0.1, 30.0.2, 30.0.3
      System Images: android-28 | Google APIs Intel x86 Atom, android-29 | Google APIs Intel x86 Atom, android-30 | Google APIs Intel x86 Atom
      Android NDK: Not Found
    Windows SDK:
      AllowDevelopmentWithoutDevLicense: Enabled
      AllowAllTrustedApps: Enabled
      Versions: 10.0.16299.0, 10.0.17134.0, 10.0.17763.0, 10.0.18362.0, 10.0.19041.0
  IDEs:
    Android Studio: Not Found
    Visual Studio: 16.9.31313.79 (Visual Studio Community 2019)
  Languages:
    Java: 1.8.0_282 - /c/Program Files/OpenJDK/openjdk-8u282-b08/bin/javac
  npmPackages:
    @react-native-community/cli: Not Found
    react: 17.0.2 => 17.0.2
    react-native: 0.65.2 => 0.65.2
    react-native-windows: ^0.65.7 => 0.65.7
  npmGlobalPackages:
    *react-native*: Not Found

Target Platform Version

10.0.19041

Target Device(s)

Desktop

Visual Studio Version

Visual Studio 2019

Build Configuration

Release

Snack, code example, screenshot, or link to a repository

FileOpener.h

#pragma once

#include "pch.h"
#include "NativeModules.h"
#include <string>

namespace RN = winrt::Microsoft::ReactNative;

namespace inspection::FileOpener {
    REACT_MODULE(FileOpener, L"FileOpener");
    struct FileOpener final {
        RN::ReactContext m_reactContext;

        REACT_INIT(Initialize)
            void Initialize(RN::ReactContext const& reactContext) noexcept;

        REACT_METHOD(openFileAsync)
        winrt::fire_and_forget openFileAsync(std::string filepath, bool showOpenWithDialog, RN::ReactPromise<void> promise) noexcept;
    };
}

FileOpener.cpp

#include "pch.h"

#include "FileOpener.h"

#include <filesystem>
#include <windows.h>
#include <winrt/Windows.Storage.h>
#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.System.h>

using namespace winrt;
using namespace winrt::Windows::Storage;
using namespace winrt::Windows::Foundation;
using namespace Windows::System;

namespace inspection::FileOpener {
    void FileOpener::Initialize(RN::ReactContext const& reactContext) noexcept {
        m_reactContext = reactContext;
    }

    winrt::fire_and_forget FileOpener::openFileAsync(std::string filepath, bool showOpenWithDialog, RN::ReactPromise<void> promise) noexcept
    try {
        std::filesystem::path fPath{ filepath };
        fPath.make_preferred();
        auto jsDispatcher = m_reactContext.JSDispatcher();

        try {
            StorageFile file{ co_await StorageFile::GetFileFromPathAsync(winrt::to_hstring(fPath.c_str())) };
            try {
                if (file) {
                    m_reactContext.UIDispatcher().Post([showOpenWithDialog, file, promise, fPath, jsDispatcher]()->winrt::fire_and_forget {
                        LauncherOptions launchOptions;
                        launchOptions.DisplayApplicationPicker(showOpenWithDialog);
                        bool success{ co_await Launcher::LaunchFileAsync(file, launchOptions) };
                        if (success) {
                            jsDispatcher.Post([promise] { promise.Resolve(); });
                        } else {
                            jsDispatcher.Post([promise, fPath] { promise.Reject(RN::ReactError{ "Unable to open File", winrt::to_string(fPath.c_str()) }); });
                        }
                    });
                } else {
                    promise.Reject(RN::ReactError{ "Unable to open File", winrt::to_string(fPath.c_str()) });
                }
            } catch (const hresult_error& ex) {
                promise.Reject(RN::ReactError{ "Unable to LaunchFileAsync for File " + filepath, winrt::to_string(ex.message()).c_str() });
            }

        } catch(const hresult_error& ex) {
            promise.Reject(RN::ReactError{ "Unable to GetFileFromPathAsync for File " + filepath, winrt::to_string(ex.message()).c_str() });
        }

    } catch(const hresult_error& ex) {
        promise.Reject(RN::ReactError{ "Unable to make path or make_preferred for File " + filepath, winrt::to_string(ex.message()).c_str() });
    }
}

Start with the linked “Using UIDispatcher with C++/WinRT” documentation and compare its example with ClipboardModule.cpp, AccessibilityInfoModule.cpp, ImageViewManagerModule.cpp, and AlertModule.cpp. Clarify how a UIDispatcher callback returns or rejects a promise, including results from FileOpenPicker or LaunchFileAsync, and ensure the documented usage does not crash.