Exe is not working while executing from the Wix installer custom action

I have an exe which I am executing using a custom action in wix installer.

During the installation when the installer executes this exe, I am getting an error logged in event viewer as follows.

Application: MSIB354.tmp
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.IO.FileNotFoundException
   at Middleware.Program.Main()

At the same time when I execute the same exe manually by double clicking its working as expected. I tried to write logs. Its not working. Even before the execution of exe, its erroring out.

This is how I have added the exe in wix installer.

<Binary Id="middlewareapp_exe" SourceFile="$(var.MyApp.ProjectDir)..\..\bin.NET\Middleware.exe" />

<CustomAction Id='MiddlewareApp' BinaryKey='middlewareapp_exe' ExeCommand='' Return='asyncNoWait'  />

<Custom Action="MiddlewareApp" After="InstallFinalize">NOT Installed</Custom>

I am suspecting a line in my code, as the error is pointing to a FileNotFoundException.

Please see my code below.

string baseAddress = "http://localhost:5000/";
                string appName = "MyApp";

                string appPath = Process.GetCurrentProcess().MainModule.FileName;
                // This is the line which I suspect. While executing the exe through MSI installer's custom action, will it get the CurrentProcess?



                eventlog.WriteEntry(appPath, EventLogEntryType.Information, 101, 1);
                // Hide the console window if it's not interactive
                if (!Environment.UserInteractive)
                {
                    var handle = GetConsoleWindow();
                    ShowWindow(handle, SW_HIDE);
                }

                RegisterInStartup(appName, appPath);

                using (WebApp.Start<Startup>(baseAddress))
                {
                    NotifyIcon trayIcon = new NotifyIcon
                    {
                        Icon = SystemIcons.Application,
                        Text = "MyApp Running",
                        Visible = true
                    };

                    // Optional: Show a balloon tip
                    trayIcon.ShowBalloonTip(3000, "MyApp", "Running in background", ToolTipIcon.Info);

                    Console.WriteLine("Server running at " + baseAddress);
                    Thread.Sleep(Timeout.Infinite); // Keeps app alive without needing console input
                }

Any idea what went wrong here? Or any suggestions in troubleshooting this issue?