itaComsolDataset: Now properly uses default input for Grids() method

applications/SoundFieldSimulation/Comsol/ComsolModelNodes/@itaComsolDataset/itaComsolDataset.m

@@ -49,6 +49,7 @@ classdef itaComsolDataset < itaComsolNode
             %source data can be given as a filter.
             %   Inputs (default):
             %   sourceDataTag (''): Tag of the source for this set (either solution or other dataset) 
+            if nargin < 2; sourceDataTag = ''; end
             gridDatasets = obj.Filter(sourceDataTag, 'grid');
         end
     end