Model doesn't contain any free variables error

Questions
5

I’m running version 3.8

array([1.670e+01, 1.440e+01, 7.600e+00, 1.080e+01, 1.000e-02, 9.000e+00,
       1.310e+01, 5.500e+00, 6.600e+00, 1.000e-03, 1.210e+01, 1.060e+01,
       1.050e+01, 1.000e-02, 3.000e+00, 6.000e+00, 5.400e+00, 1.360e+01,
       1.290e+01, 9.700e+00, 1.110e+01, 1.310e+01, 1.000e-03, 1.760e+01,
       1.000e-02, 3.600e+00, 1.555e+01, 1.190e+01, 1.800e+01, 3.600e+00,
       3.700e+00, 8.950e+00, 7.300e+00, 1.000e-03, 1.930e+01, 8.000e+00,
       1.190e+01, 1.900e+01, 8.300e+00, 1.060e+01])