MailWindow: Fix crash when selecting custom members

Elwig/Windows/MailWindow.xaml.cs

@@ -168,6 +168,7 @@ namespace Elwig.Windows {
                 .Where(m => m.IsActive)
                 .OrderBy(m => m.FamilyName)
                 .ThenBy(m => m.GivenName)
+                .Include(m => m.EmailAddresses)
                 .ToListAsync(), MemberInput_SelectionChanged);
             if (MemberCustomInput.SelectedItems.Count == 0) {
                 MemberCustomInput.ItemSelectionChanged -= MemberInput_SelectionChanged;