**Commandline:**
```
python3 pwb.py clean_sandbox -lang:ar -family:wikibooks
```
**Output:**
```
WARNING: /mnt/nfs/labstore-secondary-tools-home/meno25/core/pywikibot/tools/__init__.py:1449: UserWarning: Site wikipedia:be-tarask instantiated using different code "be-x-old"
return obj(*__args, **__kw)
Preparing to process sandbox page [[ويكي الكتب:ساحة اللعب]]
Traceback (most recent call last):
File "pwb.py", line 363, in <module>
if not main():
File "pwb.py", line 358, in main
file_package)
File "pwb.py", line 75, in run_python_file
main_mod.__dict__)
File "./scripts/clean_sandbox.py", line 301, in <module>
main()
File "./scripts/clean_sandbox.py", line 297, in main
bot.run()
File "./scripts/clean_sandbox.py", line 228, in run
delta = self.opt.delay_td - edit_delta
TypeError: unsupported operand type(s) for -: 'NoneType' and 'datetime.timedelta'
CRITICAL: Exiting due to uncaught exception <class 'TypeError'>
```
**Note:**
* The specific line in the error:
```
delta = self.opt.delay_td - edit_delta
```
was recently changed in rPWBCe3c9d3c507d2212c9e0dcacf64a05dccb890cb1d
so, it is probably the cause of this error.