OpenMW-CS: Dragging a cell of a different type (from the initial type) into the 3D view crashes OpenMW-CS

In OpenMW-CS it's possible to open a cell in the 3D view as in the screenshot.

Once the 3D view is open, additional cell records can be drag&dropped into it.

• When the 3D view was created from an exterior cell, additional exterior cells dragged into the view will be added to the scene along with already loaded ones
• When the 3D view was created from an interior cell, drag&dropping an interior cell will replace the currently loaded cell in the 3D view.

The problem

When you drag&drop an interior cell record to a 3D view created from an exterior cell record (and vice versa) OpenMW-CS crashes. The expected behaviour would be to not crash and to simply replace the currently loaded cells even when a cell of a different type is dragged into the 3D view.

The following error is recorded by openmw-cs-crash.log

*** Fatal Error ***
Address not mapped to object (signal 11)
Address: (nil)

When comparing an opened exterior and interior cells, there are differences to the 3D view.