push_tx and get 'NoneType' object is not iterable

[litterGuy]

use 1.2.11 version and nodel synced.when send a request that push_tx,then return 'NoneType' object is not iterable.

the error from debug.log is :

2022-01-19T09:12:28.081 full_node chia.rpc.rpc_server     : WARNING  Error while handling message: Traceback (most recent call last):
  File "/home/connuser/chia-blockchain/chia/rpc/rpc_server.py", line 83, in inner
    res_object = await f(request_data)
  File "/home/connuser/chia-blockchain/chia/rpc/full_node_rpc_api.py", line 520, in push_tx
    spend_bundle = SpendBundle.from_json_dict(request["spend_bundle"])
  File "/home/connuser/chia-blockchain/chia/types/spend_bundle.py", line 99, in from_json_dict
    return dataclass_from_dict(cls, json_dict)
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 72, in dataclass_from_dict
    return klass(**{f: dataclass_from_dict(fieldtypes[f], d[f]) for f in d})
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 72, in <dictcomp>
    return klass(**{f: dataclass_from_dict(fieldtypes[f], d[f]) for f in d})
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 75, in dataclass_from_dict
    return [dataclass_from_dict(get_args(klass)[0], item) for item in d]
TypeError: 'NoneType' object is not iterable

2022-01-19T09:13:28.399 full_node chia.rpc.rpc_server     : WARNING  Error while handling message: Traceback (most recent call last):
  File "/home/connuser/chia-blockchain/chia/rpc/rpc_server.py", line 83, in inner
    res_object = await f(request_data)
  File "/home/connuser/chia-blockchain/chia/rpc/full_node_rpc_api.py", line 520, in push_tx
    spend_bundle = SpendBundle.from_json_dict(request["spend_bundle"])
  File "/home/connuser/chia-blockchain/chia/types/spend_bundle.py", line 99, in from_json_dict
    return dataclass_from_dict(cls, json_dict)
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 72, in dataclass_from_dict
    return klass(**{f: dataclass_from_dict(fieldtypes[f], d[f]) for f in d})
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 72, in <dictcomp>
    return klass(**{f: dataclass_from_dict(fieldtypes[f], d[f]) for f in d})
  File "/home/connuser/chia-blockchain/chia/util/streamable.py", line 75, in dataclass_from_dict
    return [dataclass_from_dict(get_args(klass)[0], item) for item in d]
TypeError: 'NoneType' object is not iterable

how to fix it?