ValueError: [TypeError("'Decimal128' object is not iterable"), TypeError('vars() argument must have __dict__ attribute')]

[zolghadri]

Hi. I have some problem when I'm saving a document.
Beanie version is : 1.15.4

My code is like this:

from decimal import Decimal
from beanie import Document
from typing import List

class Histogram:
  timestamp : int = ...
  balance: Decimal = ...
  
class Base(Document):
 last_balances : List[Histogram] = []
 
class Master(Base):
  name: str
  current_balance: Decimal

async def main():
  await init_beanie_collections()
  master = Master(name = "John Duo", current_balance = Decimal(0) )
  await master.save()

  await master.save()
File "/usr/local/lib/python3.10/site-packages/beanie/odm/documents.py", line 409, in save
  return await self.insert(session=session, **kwargs)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/actions.py", line 212, in wrapper
  result = await f(self, *args, skip_actions=skip_actions, **kwargs)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/state.py", line 39, in wrapper
  result = await f(self, *args, **kwargs)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/state.py", line 49, in wrapper
  result = await f(self, *args, **kwargs)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/self_validation.py", line 12, in wrapper
  return await f(self, *args, **kwargs)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/documents.py", line 221, in insert
  get_dict(self, to_db=True), session=session
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/dump.py", line 15, in get_dict
  return Encoder(by_alias=True, exclude=exclude, to_db=to_db).encode(
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 77, in encode
  return self._encode(obj=obj)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 154, in _encode
  return self.encode_document(obj)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 107, in encode_document
  obj_dict[k] = encoder.encode(obj_dict[k])
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 77, in encode
  return self._encode(obj=obj)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 158, in _encode
  return self.encode_dict(obj)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 126, in encode_dict
  obj[key] = self._encode(value)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 158, in _encode
  return self.encode_dict(obj)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 126, in encode_dict
  obj[key] = self._encode(value)
File "/usr/local/lib/python3.10/site-packages/beanie/odm/utils/encoder.py", line 176, in _encode
  try:
ValueError: [TypeError("'Decimal128' object is not iterable"), TypeError('vars() argument must have __dict__ attribute')]

please help me to find and debug this problem.