EnhancedFileSystemWatcher crashes when directory does not exist

This tiny little changes fixed an issue I ran in to:

When watching a directory containing an image (png or jpg). If I "preview" the image in windows (8 in my case) and decide to rotate the image, when I close it I get an exception in OnFileChanged when checking if it is a directory. This issue could probably also occur in OnFileRenamed so I applied the same fix there.

Any thoughts?