Exception after start under VS2017

[evgenijbystrov]

I installed IsWix after VS2017. I open my project and click Tools>Launch IsWix. After showing message below IsWix opens.

[iswix-llc]

The "Launch IsWiX" takes the active document and passes the filepath to IsWiX. This error occurs when you send it a non-XML or malformed XML document. Be sure to navigate to your ProjectNameMM project and have the ProjectNameMM.wxs document open before launching IsWiX.

I guess I've always tolerated this error UI. I will leave this open and fix it so this is a better looking error box. Pull requests accepted. The code is in the AddIn and NewAddIn projects.

[iswix-llc]

Actually thats not where the code is. My bad. The stack trace clearly says where it is.

[iswix-llc]

This technically wasn't an unhandled exception. It was a poorly handled one though. I've changed the dialog to inform the user of the path of the file and that it isn't valid. Then the tool continues on starting.