nessai test suite fails with corner 2.2.2

[duncanmmacleod]

Describe the bug

The test suite fails when corner 2.2.2 is included in the test environment:

$ python -m pytest tests/test_plot.py -x
======================================== test session starts =========================================
platform linux -- Python 3.11.3, pytest-7.3.0, pluggy-1.0.0
rootdir: /home/duncan/git/nessai
configfile: pyproject.toml
plugins: cov-4.0.0
collected 75 items

tests/test_plot.py .......................................................F

============================================== FAILURES ==============================================
__________________________________________ test_corner_plot __________________________________________

live_points = array([(-4.65345777,  0.96432746, nan, nan, 0),
       (-2.21440385,  4.9681729 , nan, nan, 0),
       ( 1.67006296,  ... -3.00372179, nan, nan, 0)],
      dtype=[('x', '<f8'), ('y', '<f8'), ('logP', '<f8'), ('logL', '<f8'), ('it', '<i4')])

    def test_corner_plot(live_points):
        """Test the corner plot."""
>       fig = plot.corner_plot(live_points)

tests/test_plot.py:446:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
nessai/plot.py:58: in wrapper
    return func(*args, **kwargs)
nessai/plot.py:634: in corner_plot
    fig = corner.corner(
../../opt/mambaforge/envs/nessai/lib/python3.11/site-packages/corner/corner.py:280: in corner
    return arviz_corner(
../../opt/mambaforge/envs/nessai/lib/python3.11/site-packages/corner/arviz_corner.py:136: in arviz_corner
    fig = corner_impl(
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

xs = array([[-4.65345777,  0.96432746],
       [-2.21440385,  4.9681729 ],
       [ 1.67006296,  3.63502087],
       [ 1.55... 0.03564489],
       [ 3.90688656, -2.11997105],
       [-4.1205496 ,  4.93055757],
       [ 0.96344951, -3.00372179]])
bins = 32, range = None, axes_scale = 'linear', weights = None, color = '#02979d', hist_bin_factor = 1
smooth = 0.9, smooth1d = None, labels = array(['x', 'y'], dtype='<U4'), label_kwargs = {}
titles = array(['x', 'y'], dtype='<U4'), show_titles = True, title_fmt = '.2f', title_kwargs = {}
truths = None, truth_color = '#f5b754', scale_hist = False, quantiles = [0.16, 0.84]
title_quantiles = [0.16, 0.84], verbose = False, fig = None, max_n_ticks = 5, top_ticks = False
use_math_text = False, reverse = False, labelpad = 0.0, hist_kwargs = {'density': True}
hist2d_kwargs = {'fill_contours': True, 'levels': (0.3934693402873666, 0.8646647167633873, 0.9888910034617577), 'plot_datapoints': True, 'plot_density': True}

    def corner_impl(
        xs,
        bins=20,
        range=None,
        axes_scale="linear",
        weights=None,
        color=None,
        hist_bin_factor=1,
        smooth=None,
        smooth1d=None,
        labels=None,
        label_kwargs=None,
        titles=None,
        show_titles=False,
        title_fmt=".2f",
        title_kwargs=None,
        truths=None,
        truth_color="#4682b4",
        scale_hist=False,
        quantiles=None,
        title_quantiles=None,
        verbose=False,
        fig=None,
        max_n_ticks=5,
        top_ticks=False,
        use_math_text=False,
        reverse=False,
        labelpad=0.0,
        hist_kwargs=None,
        **hist2d_kwargs,
    ):
        if quantiles is None:
            quantiles = []
        if title_kwargs is None:
            title_kwargs = dict()
        if label_kwargs is None:
            label_kwargs = dict()

        # If no separate titles are set, copy the axis labels
        if titles is None:
            titles = labels

        # deal with title quantiles so they much quantiles unless desired otherwise
        if title_quantiles is None:
            if len(quantiles) > 0:
                title_quantiles = quantiles
            else:
                # a default for when quantiles not supplied.
                title_quantiles = [0.16, 0.5, 0.84]

        if show_titles and len(title_quantiles) != 3:
>           raise ValueError(
                "'title_quantiles' must contain exactly three values; "
                "pass a length-3 list or array using the 'title_quantiles' argument"
            )
E           ValueError: 'title_quantiles' must contain exactly three values; pass a length-3 list or array using the 'title_quantiles' argument

../../opt/mambaforge/envs/nessai/lib/python3.11/site-packages/corner/core.py:83: ValueError

I believe the incompatibility was introduced by dfm/corner.py#193.

To Reproduce

mamba create -n nessai python=3.11 corner=2.2.2 nessai=0.8.0 pytest pytest-cov
conda activate nessai
python -m pytest tests/test_plot.py -x

Expected behaviour

The tests pass

Screenshots

Additional context
Add any other context about the problem here.