transform: {
    '\\.(gql|graphql)$': [
      'graphql-let/jestTransformer'
    ],
}

Invalid return value:
      `process()` or/and `processAsync()` method of code transformer found at 
      "/root/repo/node_modules/jest-transform-graphql/index.js" 
      should return an object or a Promise resolving to an object. The object 
      must have `code` property with a string of processed code.
      This error may be caused by a breaking change in Jest 28:
      https://jestjs.io/docs/upgrading-to-jest28#transformer
      Code Transformation Documentation:
      https://jestjs.io/docs/code-transformation