Refs #9037 Logic Error fixed

This was purely down to my own bad understanding of how numpy worked. It should now work as expected.

I also removed a debugging print statement as that was missed in another ticket.
Refs #9037 Streamlined check for an array

found out that groupget was already doing a check (it seems i did it and forgot about it) so the check in calcres wasn't required.

The array accessing in groupget has also been streamlined
Merge branch 'bugfix/9037_refl_numpy_fix' into release/3.1.x