Bugfix: Solves HEADLESS crash on Macs.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@1349 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/settings/FileSetting.java

@@ -46,6 +46,7 @@ public class FileSetting extends Setting
 	
 	private static FileSelector defaultSelector()
 	{
+		try {
 			return new FileSelector()
 			{
 				JFileChooser choose = new JFileChooser();
@@ -60,6 +61,13 @@ public class FileSetting extends Setting
 				}
 			};
 		}
+		// Catch any problems that occur when running in headless mode
+		// (e.g. the command-line version of PRISM)
+		// (in this case, you don't need this object anyway)
+		catch (HeadlessException e) {
+			return null;
+		}
+	}
     
 	private boolean validFile;
 	private FileSelector selector;