Getting past a none type error

[buran]

There are two possible approaches

One approach is EAFP - Easier to ask for forgiveness than permission
Note the try/except block to handle the error

import requests
import time
from bs4 import BeautifulSoup
 
UID_start = 58217
UID_end = 58221
 
for UID in range(UID_start, UID_end):
    print UID
    page = requests.get("http://forum.shipspotting.com/index.php?action=profile;u=" + str(UID)) #I have altered the link for this post to work
    soup = BeautifulSoup(page.content, 'html.parser')
    div = soup.find("div", {'class':'content'})
    signature = div.find("div", {'class':"signature"})
    user = div.find('tr', {'class':'titlebg'}).find('td').text.split(' ')[-1].strip()
    try:
        print('User: {}\nSigniture: {}'.format(user, signature.text))
    except AttributeError:
        print(div.find('tr', {'class':'windowbg'}).text.strip())
    print
    time.sleep(1) # add some sleep between requests

The otehr one is LBYL - Look before you leap
In this case check what you work with

import requests
import time
from bs4 import BeautifulSoup
 
UID_start = 58217
UID_end = 58221
 
for UID in range(UID_start, UID_end):
    print UID
    page = requests.get("http://forum.shipspotting.com/index.php?action=profile;u=" + str(UID)) #I have altered the link for this post to work
    soup = BeautifulSoup(page.content, 'html.parser')
    div = soup.find("div", {'class':'content'})
    signature = div.find("div", {'class':"signature"})
    if signature is not None:
        user = div.find('tr', {'class':'titlebg'}).find('td').text.split(' ')[-1].strip()
        print('User: {}\nSigniture: {}'.format(user, signature.text))
    else:
        print(div.find('tr', {'class':'windowbg'}).text.strip())
    print
    time.sleep(1) # add some sleep between requests

in both cases the output is

Output:
58217
User: nikond3100cam2
Signiture: <a href="http://www.nikon-d3100.com">Nikon D3100</a> - Digital Camera
D3100 NikonNikon DSLR D3100Nikon D3100Nik

58218
User: alvinswaim
Signiture:

58219
The user whose profile you are trying to view does not exist.

58220
The user whose profile you are trying to view does not exist.