How can I can not raise error in mutations with graphene django?

I'm using graphene-django-cud for mutations. But I can't raise any GraphQLError, ValueError or Exception in mutations. Like in before_mutate() or any validate_ method. The process just stop with out any error message. Then return null for the instance and message.

@classmethod
def before_mutate(cls, root, info, input, id):
    print("before_mutate")
    from graphql import GraphQLError
    raise GraphQLError(f"The observation with id {id} doesn't exists")

@classmethod
def validate_name(cls, root, info, value, input, id, obj):
    print("validate_name")
    raise ValueError(f"The observation with id {id} doesn't existssss")

Anyone met this before? Thanks in advance!

Now I figured out what's going on.

It's not from graphene-django-cud, it's from graphene. I have to add try/except to catch the error, then return a GraphQLError.

from graphene import Field
from graphene_django_cud.mutations import DjangoCreateMutation
from graphql import GraphQLError
from .models import Demo
from .types import DemoType
import logging
import traceback

class DemoCreateMutation(DjangoCreateMutation):
    demo = Field(DemoType)

    class Meta:
        model = Demo

    @classmethod
    def mutate(cls, root, info, input):
        try:
            return super().mutate(root, info, input)
        except Exception as e:
            logging.error(str(e))
            return GraphQLError(traceback.format_exc())

    @classmethod
    def before_mutate(cls, root, info, input, id):
        raise GraphQLError(f"The Demo {id} doesn't exists")

    @classmethod
    def validate_name(cls, root, info, value, input, id, obj):
        raise ValueError(f"The Demo {id} doesn't existssss")