macosx: another sanity check since in rare circumstances an input's URL may be nil

modules/gui/macosx/MainWindow.m

@@ -644,12 +644,18 @@ static VLCMainWindow *_o_sharedInstance = nil;
                 aString = [o_url absoluteString];
         }
 
+        if ([aString length] > 0) {
             [self setTitle: aString];
             [[[VLCMain sharedInstance] voutController] updateWindowsUsingBlock:^(VLCVideoWindowCommon *o_window) {
                 [o_window setTitle:aString];
             }];
 
             [o_fspanel setStreamTitle: aString];
+        } else {
+           [self setTitle: _NS("VLC media player")];
+            [self setRepresentedURL: nil];
+        }
+
         vlc_object_release(p_input);
     } else {
         [self setTitle: _NS("VLC media player")];