class_docstr: Test running model for a scalar ODE with 1 parameter
code: def test_number_of_params(self):
      with pytest.raises(
          ValueError, match="Argument n_theta must be positive"
      ):
          DifferentialEquation(
              func=self.system,
              t0=0,
              times=self.times,
              n_states=1,
              n_theta=0,
          )
  
imports: import warnings
  import numpy
  import pytensor
  import pytensor.tensor
  import pytest
  from scipy.stats import norm
  import pymc
  from pymc.ode import DifferentialEquation
  from pymc.testing import fast_unstable_sampling_mode
label_desc: Use image node_id 8 for calling the TestErrors obj's underlying member method code with example usage: obj.test_number_of_params() without return types