or you can just catch the exception, i guess
you don't get errors from handled exceptions and you can also test if the problem is because of different application creating the drawing, or because of the potential errors
Yes, you can trap the COMexception (not a simple Exception), but doing so ( did you?), you still have to set the variable DWGCHECK=2 and try to open the file again in order to get, may be, the drawing opened.
I think that a better aproach is to set DWGCHECK=2, then try to open the drawing as usual, get the drawing opened and check the DwgFileWasSavedByAutodeskSoftware property in order to take some action.