Avoid errors from previously faulty bounds check

Remove the check isntead and just catch the only possible exceptions.
This is more pythonic and avoids the need to worry about off-by-one
errors. Keep the greater than 0 check to prevent access by negative
numbers which while possible would look rather weird.

Change-Id: I31de64a746c5712d08a7c2ac1a14725989d2c7b4
Merge commit 'refs/changes/08/1608/1' of https://www.studentrobotics.org/gerrit/comp/srcomp-http