don't check surface_following_distance when lld_mode is not OFF

Author: rickwierenga

pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py

@@ -1996,9 +1996,13 @@ async def aspirate(
       surface_following_distance = _fill_in_defaults(surface_following_distance, [0.0] * n)
 
     # check if the surface_following_distance would fall below the minimum height
+    # if lld is enabled, we expect to find liquid above the well bottom so we don't need to raise an error
     if any(
-      well_bottoms[i] + liquid_heights[i] - surface_following_distance[i] - minimum_height[i]
-      < -1e-6
+      (
+        well_bottoms[i] + liquid_heights[i] - surface_following_distance[i] - minimum_height[i]
+        < -1e-6
+      )
+      and lld_mode[i] == STARBackend.LLDMode.OFF
       for i in range(n)
     ):
       raise ValueError(