UnboundLocalError in ip.py:verify_ip_address when all IP check URLs fail

[markthepixel]

Description

When all IP-check URLs fail (e.g., proxy is down), verify_ip_address() raises:

UnboundLocalError: cannot access local variable 'exception' where it is not associated with a value

instead of the intended InvalidIP exception.

Root cause

In Python 3, except ... as var deletes var when the except block exits (PEP 3110). So after the last iteration's except block runs, exception is deleted, and line 120 can't access it.

# ip.py lines 104-120
exception = None                    # initial assignment
for url in URLS:
    try:
        ...
    except (...) as exception:      # Python 3 deletes 'exception' after this block exits
        pass
raise InvalidIP(f"Failed to get IP address: {exception}")  # UnboundLocalError

Fix

last_exception = None
for url in URLS:
    try:
        ...
    except (requests.exceptions.ProxyError, requests.RequestException, InvalidIP) as exception:
        last_exception = exception
raise InvalidIP(f"Failed to get IP address: {last_exception}")

Reproduction

Call verify_ip_address() with a proxy that can't reach any of the IP-check URLs (all 5 must fail).

[markthepixel]

@coryking obvi upstream, but would be worth the fix here