.NET (Windows Forms) : Update Textbox with output from external script

Question

I want to create a small C#-program which has multiple buttons which execute a Powershell script and put the results asynchronously into a textbox. I wanted to do it the following way:

private void Button_Click(object sender, RoutedEventArgs e)
        {
            var ps1File = @"SomeScript.ps1";
            Process proc = new System.Diagnostics.Process();

            proc.StartInfo.FileName = "powershell.exe";
            proc.StartInfo.Arguments = $"-NoProfile -ExecutionPolicy unrestricted \"{ps1File}\"";
            proc.StartInfo.UseShellExecute = false;
            proc.StartInfo.CreateNoWindow = true;
            proc.StartInfo.RedirectStandardOutput = true;
            proc.StartInfo.RedirectStandardError = true;
  
            var err = "";    
            tbConsole.Text = "Loading printers ...";

            proc.OutputDataReceived += (o, e2) =>
            {
                if (e2.Data == null) err = e2.Data;
                else
                {
                    if (e2.Data == null) err = e2.Data;
                    else tbConsoleError.AppendText(e2.Data);
                }
            };

            proc.ErrorDataReceived += (o, e2) =>
            {
                if (e2.Data == null) err = e2.Data;
                else tbConsoleError.AppendText(e2.Data);
            };

            proc.Start();

            // and start asynchronous read
            proc.BeginOutputReadLine();

            proc.BeginErrorReadLine();
            // wait until it's finished in your background worker thread
            proc.WaitForExit();
            tbConsole.AppendText("... finished");    
        }

Now when I hit the button the sript runs but while editing the textboxes it gives me an error that I cannot edit the textbox as it is managed by a different thread.

When I now try to edit my code to use "invoke" and delegate I find that my MainWindow (objet-reference: "this") does not have an "invoke"-method. What am I doing wrong?