TypeError: bad operand type for unary -: 'NoneType' when running PNN_HCAS_area_repair.py

[OldGlycine]

When I tried to run PNN_HCAS_area_repair.py, an error occured

Traceback (most recent call last):
File "d:\Study\REASSURE-main\ICLR\Experiments\HCAS\PNN_HCAS_area_repair.py", line 61, in
PNN_HCAS_advanced(num, n)
File "d:\Study\REASSURE-main\ICLR\Experiments\HCAS\PNN_HCAS_area_repair.py", line 20, in PNN_HCAS_advanced
[item for item in all_linear_regions if not verify(item[0], item[1], item[2], target_model.layers, right_label=right_label)]
File "d:\Study\REASSURE-main\ICLR\Experiments\HCAS\PNN_HCAS_area_repair.py", line 20, in
[item for item in all_linear_regions if not verify(item[0], item[1], item[2], target_model.layers, right_label=right_label)]
File "d:\Study\REASSURE-main\ICLR\Experiments\HCAS....\tools\linear_region.py", line 157, in verify
res = res and (solve_LP(np.matmul(P[i], C), A, b, None, is_minimum=False) + np.matmul(P[i], d) <= qu[i])
File "d:\Study\REASSURE-main\ICLR\Experiments\HCAS....\tools\gurobi_solver.py", line 48, in solve_LP
return -linprog(-c, A, b, bounds).fun
TypeError: bad operand type for unary -: 'NoneType'

I haven't change any codes and I can't figured out why it happend, could you help me? Thank you very much!