serialize from GraphqlScalarType not allow to return null

[xs3213213213]

i am using the version 16.6.0
I have implemented: GraphqlScalarType like this:

`

export const IntScalar = new GraphqlScalarType ({
   ...GraphQLInt,
    serialize(value) {
       if(value === 10000) {
          return null;
       }

    return value;
   }

})

`

im getting expected IntScalar.Serialize(10000) to return non-nullable value retrun null

why cant i return null?

[IvanGoncharov]

@xs3213213213 Because scalars values are different from null.
You can't mix custom scalar values and null, see here:
https://spec.graphql.org/draft/#sel-EANTLEHJIMDJBA58K