list index out of range: trouble importing psk

[OrionLion8]

Hi,
I'm trying to import this psk. For some reason I've previously been able to open it, but I didn't save the project that I opened it in; when I try to import it into a new project, it gives me this error screen.

Here's the psk:
WS2_common_island_psk.zip.
I tried it on Blender 2.83 and Blender 2.90.
Sorry! Any assistance would be greatly appreciated.