Python-Numba多项式根下误差

我创建了一个函数,给定系数的范围,用这些系数构造多项式,并输出其所有根的列表。然而,Numba不喜欢它。是这样的:

import math
import numpy as np
import itertools
from numba import jit
from sympy.solvers import solve
from sympy import Symbol
from sympy import Poly

@jit
def polyn(ranges=[[-20,20],[-20,20],[-20,20],[-20,20]],step=4):
    l = []
    x = Symbol('x')
    rangl = [np.linspace(i[0],i[1],math.floor((i[1]-i[0])/step)) for i in ranges]
    coeffl = iter(itertools.product(*rangl))
    leng = 1
    for i in rangl:
        leng *= len(i)
    for i in range(0, leng):
        a = solve(Poly(list(next(coeffl)),x),x)
        for j in a:
            l.append(j)
    return np.array(l)

当我尝试运行此程序时,它会输出一个神秘的: AssertionError:在对象处失败(对象模式前端) 我不明白。。。有人能帮忙吗?