Currently, the last bin of the histograms with the spline corrections is 0. This will be fixed for future calibrations, but in the meantime, we should use the N-1 bins of the histogram to provide the extrapolation of the correction. This MR provides a fix to use that bin instead of the last one.
Tagging the conveners @mswiatlo @camacho @mleblanc @mspalla @haweber, and @dgillber who pointed out that there was a potential issue in the calibration.