iminuit hangs when trying to visualize step function

[2xB]

The following minimization seemingly hangs when running the following in Jupyter. @l-althueser did some investigations and found out that this does not occur when avoiding the visualization, e.g. by running this as a Python script or by calling migrad like unused = m.migrad() instead. It also hangs when just calling m.visualize() and when using a KeyboardInterrupt after that call, it occurs in /usr/local/lib64/python3.10/site-packages/iminuit/util.py:1560, in _smart_sampling(f, xmin, xmax, start, tol).

Used iminuit version: 2.23.0.

from iminuit import Minuit
from iminuit.cost import LeastSquares
import numpy as np

def model(x, c1):
    c2 = 100
    res = np.zeros(len(x))
    mask = x < 47
    res[mask] = c1
    res[~mask] = c2
    return res

xtest = np.linspace(0,74)
ytest = xtest*0+1
ytesterr = ytest

least_squares = LeastSquares(xtest, ytest, ytesterr, model)

m = Minuit(least_squares, c1=1)
m.print_level = 3
m.migrad()
#m.hesse()

[HDembinski]

Thanks for the report and the reproducer, I will fix this asap.