[MonoDevelop] Fix of 77361

[John Luke]

Jacob Ilsø Christensen wrote:
> Hi.
>
> The attached patch fixes bug 77361 
> (http://bugzilla.ximian.com/show_bug.cgi?id=77361). Does it look good 
> to commit?
> If so I will implement the same check for the other language bindings.
>
How about:

if (fileName == null || fileName.Length == 0)
	return false;