Чем визвана ошибка? ERROR:asyncio:Task exception was never retrieved future: <Task finished name='Task-8'

Question

Чем визвана ошибка? ERROR:asyncio:Task exception was never retrieved future: <Task finished name='Task-8'

coro=<Dispatcher._process_polling_updates() done, defined at /data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/dispatcher.py:407> exception=IntegrityError('UNIQUE constraint failed: user.user_id')>
Traceback (most recent call last):
File "/data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/dispatcher.py", line 415, in _process_polling_updates
for responses in itertools.chain.from_iterable(await self.process_updates(updates, fast)):
File "/data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/dispatcher.py", line 235, in process_updates
return await asyncio.gather(*tasks)
File "/data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/handler.py", line 116, in notify
response = await handler_obj.handler(*args, **partial_data)
File "/data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/dispatcher.py", line 256, in process_update
return await self.message_handlers.notify(update.message)
File "/data/data/ru.iiec.pydroid3/files/arm-linux-androideabi/lib/python3.9/site-packages/aiogram/dispatcher/handler.py", line 116, in notify
response = await handler_obj.handler(*args, **partial_data)
File "<string>", line 54, in start
File "/storage/emulated/0/Sestem.bot/RTsuperbot/db.py", line 21, in add_user
self.cursor.execute("INSERT INTO 'user' ('user_id') VALUES (?)", (user_id,))
sqlite3.IntegrityError: UNIQUE constraint failed: user.user_id