fix dispense96 without volume tracking

Author: rickwierenga

pylabrobot/liquid_handling/liquid_handler.py

@@ -1772,9 +1772,13 @@ async def dispense96(
       for well, channel in zip(containers, self.head96.values()):
         # even if the volume tracker is disabled, a liquid (None, volume) is added to the list
         # during the aspiration command
-        liquids = channel.get_tip().tracker.remove_liquid(volume=volume)
-        reversed_liquids = list(reversed(liquids))
-        all_liquids.append(reversed_liquids)
+        if channel.get_tip().tracker.is_disabled or not does_volume_tracking():
+          reversed_liquids = [(None, volume)]
+          all_liquids.append(reversed_liquids)
+        else:
+          liquids = channel.get_tip().tracker.remove_liquid(volume=volume)
+          reversed_liquids = list(reversed(liquids))
+          all_liquids.append(reversed_liquids)
 
         if not well.tracker.is_disabled and does_volume_tracking():
           for liquid, vol in reversed_liquids: