csrf = soup.find("input") ['value'] TypeError: 'NoneType' object is not subscriptable

Question

When i run below code in the following format, python.exe sql-lab-02.py https://ace61f2f1f1e76b9c0931a7400310060.web-security-academy.net "admin" I get the following error csrf = soup.find("input") ['value'] TypeError: 'NoneType' object is not subscriptable . I would be glad to figure out how go about this error.

import sys
import urllib3
#from html.parser import HTMLParser
#import markupbase
from bs4 import BeautifulSoup
#from lxml import html

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

proxies = {'http':'http://127.0.0.1:8081', 'https': 'http://127.0.0.1:8081'}

def get_csrf_token(s, url):
    r = s.get(url, verify=False, proxies=proxies)
    #print(r.text)
    soup = BeautifulSoup(r.text, 'html.parser')
    #soup = BeautifulSoup(r.text, features='html')
    #print(soup.prettify())
    csrf = soup.find("input") ['value']
    print(csrf)


def exploit_sqli(s, url, payload):
    csrf = get_csrf_token(s, url)
    # incomplete

if __name__ == "__main__":
    try:
        url=sys.argv[1].strip()
        sqli_payload = sys.argv[2].strip()
    except IndexError:
        print("[-] Usage: %s <url> <sql-payload>" % sys.argv[0])
        print('[-] Example: %s www.example.com "1=1"' %sys.argv[0])
        sys.exit(-1)

    s = requests.Session()
    #print(s.text)

    if exploit_sqli(s, url, sqli_payload):
        print('[+] SQL injection successful! We have logged you in as administrator user.')
    else:
        print('[+] SQL injection unsuccessful!')

The error is generated in line 39, in if exploit_sqli(s, url, sqli_payload): line 24, in exploit_sqli csrf = get_csrf_token(s, url)

in line 19, in get_csrf_token csrf = soup.find("input") ['value']