Plotting with no lpo

[brandonwkerns]

Plotting does not work when there are no LPOs. The script seems to crash. Error message:

"lpt_run.py" [dos] 258L, 13150C                                                                                                       117,37        44%
"""
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/matplotlib/transforms.py", line 2772, in get_transformed_points_and_affine
    self._revalidate()
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/matplotlib/transforms.py", line 2757, in _revalidate
    self._transform.transform_path_non_affine(self._path)
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/matplotlib/transforms.py", line 2431, in transform_path_non_affine
    return self._a.transform_path_non_affine(path)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/cartopy/mpl/geoaxes.py", line 170, in transform_path_non_affine
    new_vertices = self.target_projection.quick_vertices_transform(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/cartopy/crs.py", line 1377, in quick_vertices_transform
    self.y_limits[0] <= ys.min() and
                        ^^^^^^^^
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/site-packages/numpy/core/_methods.py", line 45, in _amin
    return umr_minimum(a, axis, None, out, keepdims, initial, where)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: zero-size array to reduction operation minimum which has no identity
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/disk/orca/bkerns/lib/lpt/lpt-python-public/ERA5/lpt_run.py", line 258, in <module>
    lpt_driver(dataset,plotting,output,lpo_options,lpt_options, merge_split_options, mjo_id_options, sys.argv)
  File "/home/disk/orca/bkerns/lib/lpt/lpt-python-public/lpt/lpt_driver.py", line 49, in lpt_driver
    p.starmap(lpt.helpers.do_lpo_calc,
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/multiprocessing/pool.py", line 375, in starmap
    return self._map_async(func, iterable, starmapstar, chunksize).get()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/disk/orca/bkerns/anaconda3/envs/meteo_3.11/lib/python3.11/multiprocessing/pool.py", line 774, in get
    raise self._value
ValueError: zero-size array to reduction operation minimum which has no identity
(meteo_3.11) FAIL