c# - Outlook VSTO - How to check if MailItem exist (new email dialog is open and is active inspector)

Question

I have code like this

var mi = MyAddIn.Application.ActiveInspector().CurrentItem as MailItem;

if (mi != null)
{
    mi.Attachments.Add(myFilePath);
}

The problem with this code is that it assumes that new mail dialog will be opened (the ActiveInspector CurrentItem is a MailItem). However, that is not always so in my case.

If that is not the case, then above code getting mi will throw NullReferenceException.

How do I check if I have new mail dialog opened and if so then use above line to get it; otherwise create new MailItem (new mail dialog)?

I am trying to do something like this:

var mi;

if (MyAddIn.Application.ActiveInspector().CurrentItem != null)
{
    // get existing
    mi = MyAddIn.Application.ActiveInspector().CurrentItem as MailItem;
}
else 
{
    // otherwise, create new one
    mi = MyAddIn.Application.CreateItem(Microsoft.Office.Interop.Outlook.OlItemType.olMailItem);
}

// now use it to attach file   
if (mi != null)
{
    mi.Attachments.Add(myFilePath);
}