Posterior plot errors with boolean array

When passed a boolean array, plot_posterior fails with the following error because np.histogram assumes that subtraction is defined on the array:

TypeError('numpy boolean subtract, the `-` operator, is not supported, use the bitwise_xor, the `^` operator, or the logical_xor function instead.')

This example reproduces the error:

import numpy as np
import arviz as az

data = np.random.choice(a=[False, True], size=(4, 100))
az.plot_posterior(data)

[ahartikainen]

We should use bar graph with counts for bool data, not hist.

[sethaxen]

I’d expect the second, even though the first option is easier.