Assemble: fixed small bug with SIRT reconstructions

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

5_reconstruction/GtAssembleVol3D.m

@@ -281,7 +281,9 @@ classdef GtAssembleVol3D < handle
 
             obj.volumes.complete.phases = volumePIDs;
             obj.volumes.complete.grains = volumeGIDs;
-            obj.volumes.complete.dmvol = volumeDM;
+            if (assemble_6D)
+                obj.volumes.complete.dmvol = volumeDM;
+            end
 
             % Autosaving
             if (obj.localPar.autosave)