When snake doesn't grow, the last segment (new tail) should interpolate from the old tail's position (previous[segmentIndex]), not from the second-to-last segment (previous[segmentIndex-1]) which didn't move.
When snake doesn't grow, the last segment (new tail) should interpolate from the old tail's position (previous[segmentIndex]), not from the second-to-last segment (previous[segmentIndex-1]) which didn't move.