At the last paragraph, says: Also, note that you can’t drop them by pressing the Q key either yet.
But we actually added the _drop_entity function when we press Q :
# Replace the existing code block where we checked for the "drop" input action with the following. elif event.is_action_pressed("drop") and _gui.blueprint: if is_on_ground: global_mouse_position) = null
Thanks, fixing it today.