pyiem.plot.pretty_bins IndexError

[akrherz]

This is suboptimal

>>> from pyiem.plot import pretty_bins
>>> pretty_bins(21.5, 9886.5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/akrherz/projects/pyIEM/src/pyiem/plot/util.py", line 105, in pretty_bins
    return centered_bins(maxval - center, on=center, bins=bins)
  File "/home/akrherz/projects/pyIEM/src/pyiem/plot/util.py", line 127, in centered_bins
    step = avail[np.digitize(step, avail)]
IndexError: list index out of range