find null in where

[andrei0807]

I am going to get some field value is null.
but I got error.

const findResult: User[] = await this.userRepository.find({where: {group_id: null}});

src/controllers/user.controller.ts:145:72 - error TS2322: Type 'null' is not assignable to type 'PredicateComparison<string | undefined> | ((string | undefined) & ShortHandEqualType) | undefined'.

145     const findResult: User[] = await this.userRepository.find({where: {group_id: null}});
       

How can I solve this issue?
Please help me