How do I convert a string containing bracket or minus numbers to a list in python?

Question

arr ="[[1,2,3,4],[54,32,-10,-3],[]]"

without_space=[]

for i in arr:
    if len(i)!=0:
        without_space.append(i)

without_bracket=[]
array=[]
for i in without_space:
    if i.startswith("[") and i.endswith("]"):
        i=i[1:-2]
    elif i.startswith("["):
        i=i[1:]
    elif i.endswith("]"):
        i=i[:-1]

    without_bracket.append(i)

print(without_bracket)

I code this but it doesn't work properly.

I want a list to be given to sorting algorithms and sorted by algorithm. If the user accidentally or unknowingly enters values ​​that are not suitable for the array structure that I will use, I want to correct them..ı have this string but ı want to print. This list may be change. It may contain spaces or anything that I cannot use in sorting algorithms.

[[1,2,3,4],[54,32,-10,-3]]  input

[1,2,3,4,54,32,-10,-3]  output