code: def test_missing_sql_type():
      class CustomType(BaseModel):
          @classmethod
          def __get_validators__(cls):
              yield cls.validate
  
          @classmethod
          def validate(cls, v):  # pragma: no cover
              return v
  
      with pytest.raises(ValueError):
  
          class Item(SQLModel, table=True):
              id: Optional[int] = Field(default=None, primary_key=True)
              item: CustomType
  
imports: from typing import Optional
  import pytest
  from pydantic import BaseModel
  from sqlmodel import Field, SQLModel
label_desc: Use image node_id 1 for calling a global function with example usage: test_missing_sql_type() and returns: v