We're relying on Uri in the http://github.com/dotnet/project-system, to represent paths. Testing our path handling code, I found that Uri throws IndexOutOfRangeException (instead of UriFormatException) in the following situations:

new Uri("/\\‎//", UriKind.Absolute);
new Uri("\\/\u200e", UriKind.Absolute);
new Uri("/\\\\-Ā\r", UriKind.Absolute);
new Uri("\\\\\\\\\\‎", UriKind.Absolute);