cp.element.parentNode has no properties

Directory structure:
Marketing
DPTest
DpTestA
DpTestB
DpTestC

A user on Geuze and a user on Constantine in directory DpTestC.

The user on Geuze drags directory DpTestC from the main pane to DpTestA in the directory tree. On confirmation of the move, the following error appears on both Geuze and Constantine:
cp.element.parentNode has no properties
[Break on this error] cp.element.parentNode.removeChild(cp.element);