how to solve this pydantic validation issue?

An error occurred while processing your query: 2 validation errors for
Answer answer.TableData Input should be a valid dictionary or
instance of TableData [type=model_type, input_value=None,
input_type=NoneType]
For further information visit https://errors.pydantic.dev/2.7/v/model_type answer.str Input should
be a valid string [type=string_type, input_value=None,
input_type=NoneType]
For further information visit https://errors.pydantic.dev/2.7/v/string_type <class ‘str’>

here is my pydantic class which I am using for extracting data from LLM response:

def fix_json_string(input_str):
    # Manually escape backslashes first
    escaped_str = input_str.replace("\", "\\")
    # Escape other problematic characters
    escaped_str = escaped_str.replace("n", "\n")
    escaped_str = escaped_str.replace("r", "\r")
    escaped_str = escaped_str.replace("t", "\t")
    escaped_str = escaped_str.replace('"', '\"')
    escaped_str = escaped_str.replace("[", "\[")
    escaped_str = escaped_str.replace("]", "\]")
    escaped_str = escaped_str.replace("(", "\(")
    escaped_str = escaped_str.replace(")", "\)")
    escaped_str = escaped_str.replace("^", "\^")
    escaped_str = escaped_str.replace("$", "\$")
    escaped_str = escaped_str.replace("*", "\*")
    escaped_str = escaped_str.replace("+", "\+")
    escaped_str = escaped_str.replace("?", "\?")
    escaped_str = escaped_str.replace("|", "\|")
    escaped_str = escaped_str.replace(".", "\.")
    escaped_str = escaped_str.replace("'", "\'")
    return escaped_str


class TableData(BaseModel):
    # data: Optional[Dict[str, List[Any]]]
    data: Union[Dict[str, List[Any]], List[Dict[str, Any]]]
    answer: Optional[str]

    @classmethod
    def from_json(cls, json_str):
        try:
            fixed_json_str = fix_json_string(json_str)
            data = json.loads(fixed_json_str)  # Ensure the string is valid JSON
            return cls(**data)
        except json.JSONDecodeError as e:
            print(f"JSON decode error: {e}")
            return None
        except ValidationError as e:
            print(f"Validation error: {e}")
            return None


    class Answer(BaseModel):
        answer: Union[TableData, str] = Field
        sql: Union[str, Any] = Field
    
        @classmethod
        def from_json(cls, json_str):
            try:
                fixed_json_str = fix_json_string(json_str)
                data = json.loads(fixed_json_str)  # Ensure the string is valid JSON
                return cls(**data)
            except json.JSONDecodeError as e:
                print(f"JSON decode error: {e}")
                return None
            except ValidationError as e:
                print(f"Validation error: {e}")
                return None