LUMOS 'Index exceeds 0' error

[Alfie58]

Can I check the meaning of this error message:- 'Index exceeds the number of array elements. Index must not exceed 0.'

It has occurred, in this instance, when I simulate a long luminaire in a heptagonal room - the luminaire height is slightly less than the heigh of the room. The error occurs wherever the luminaire is placed - inside or outside of the room.

[Alfie58]

I've found the answer to the issue (above). It was simply that I had failed to set a spectrum for the luminaire.