Descend the array in the right way

Summary:
Detected by cppcheck as Opposite inner 'if' condition leads to a dead code block (outer condition is 'j>0' and inner condition is 'j==0').
The array is 0 based, therefore [0-4].

Test Plan: make test passes

Reviewers: Krita, dkazakov

Reviewed By: Krita, dkazakov

Subscribers: dkazakov

Tags: Krita

Differential Revision: https://phabricator.kde.org/D15905