graphql-resolvers: typescript fails for BigInt

[Andrei-Stepanov]

    "graphql": "^15.5.1",
    "graphql-bigint": "^1.0.0",
    "@types/graphql-bigint": "^1.0.0"

Hello,

I am trying to write code:

import BigInt from 'graphql-bigint'

const ExampleType = new GraphQLObjectType({
  name: 'ExampleType',
  fields: () => ({
    version: { type: GraphQLString },
    timestamp: { type: BigInt },
  }),
});

This gives error message:

Type '() => { version: { type: graphql.GraphQLScalarType; }; timestamp: { type: GraphQLScalarType; }; }' is not assignable to type 'Thunk<GraphQLFieldConfigMap<any, any>>'.
  Type '() => { version: { type: graphql.GraphQLScalarType; }; timestamp: { type: GraphQLScalarType; }; }' is not assignable to type '() => GraphQLFieldConfigMap<any, any>'.
    Type '{ version: { type: graphql.GraphQLScalarType; }; timestamp: { type: GraphQLScalarType; }; }' is not assignable to type 'GraphQLFieldConfigMap<any, any>'.
      Property 'timestamp' is incompatible with index signature.
        Type '{ type: GraphQLScalarType; }' is not assignable to type 'GraphQLFieldConfig<any, any, { [argName: string]: any; }>'.
          Types of property 'type' are incompatible.
            Type 'GraphQLScalarType' is not assignable to type 'GraphQLOutputType'.
              Type 'GraphQLScalarType' is missing the following properties from type 'GraphQLEnumType': getValues, getValuets(2322)
definition.d.ts(447, 3): The expected type comes from property 'fields' which is declared here on type 'Readonly<GraphQLObjectTypeConfig<any, any>>'
(property) fields: graphql.Thunk<graphql.GraphQLFieldConfigMap<any, any>>

Work-around, however I am not sure this is correct:

    timestamp: { type: BigInt as graphql.GraphQLOutputType },