AR Model Sample fails

[gibbs-hmm]

import timesynth as ts

Initializing TimeSampler

time_sampler = ts.TimeSampler(stop_time=20)

Sampling regular time samples

regular_time_samples = time_sampler.sample_regular_time(num_points=500)

Initializing AR(2) model
ar_p = ts.signals.AutoRegressive(ar_param=[1.5, -0.75])
ar_p_series = ts.TimeSeries(signal_generator=ar_p)
samples = ar_p_series.sample(regular_time_samples)

Fails with error
Traceback (most recent call last):
File "", line 1, in
File "/home/bill/mambaforge/envs/nn/lib/python3.11/site-packages/timesynth/timeseries.py", line 63, in sample
signal = self.signal_generator.sample_next(t, samples[:i - 1], errors[:i - 1])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/bill/mambaforge/envs/nn/lib/python3.11/site-packages/timesynth/signals/ar.py", line 54, in sample_next
ar_value = np.sum(ar_value) + noise
^^^^^^^^^^^^^^^^
File "<array_function internals>", line 200, in sum
File "/home/bill/mambaforge/envs/nn/lib/python3.11/site-packages/numpy/core/fromnumeric.py", line 2324, in sum
return _wrapreduction(a, np.add, 'sum', axis, dtype, out, keepdims=keepdims,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/bill/mambaforge/envs/nn/lib/python3.11/site-packages/numpy/core/fromnumeric.py", line 86, in _wrapreduction
return ufunc.reduce(obj, axis, dtype, out, **passkwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: setting an array element with a sequence. The requested array has an inhomogeneous shape after 1 dimensions. The detected shape was (2,) + inhomogeneous part.

Running with Python 3.11.3