Merge pull request #164 from github-for-unity/fixes/nice-io

NiceIO Exception Fix

Author: shana

src/GitHub.Api/IO/NiceIO.cs

@@ -62,7 +62,7 @@ private static StringComparison PathStringComparison
         public NPath(string path)
         {
             if (path == null)
-                throw new ArgumentNullException();
+                throw new ArgumentNullException("path");
 
             path = ParseDriveLetter(path, out _driveLetter);