fatal error: concurrent map writes

func getGBInstance() *growthbook.GrowthBook {
    context := growthbook.NewContext().
       WithClientKey("keyxxxxx").
       WithCacheTTL(10 * time.Second)

    gb := growthbook.New(context)
    gb.LoadFeatures(&growthbook.FeatureRepoOptions{
       AutoRefresh: true,
    })

    return gb
}

func evaluateFeature(gb *growthbook.GrowthBook, attVal string) bool {
    gb.WithAttributes(growthbook.Attributes{"id": attVal})
    rs := gb.EvalFeature("enable-dark-mode").On
    return rs
}
func BenchmarkEvaluateFeatureParallel(b *testing.B) {
    gbInstance = getGBInstance()
    b.ResetTimer()

    b.RunParallel(func(pb *testing.PB) {
       var wg sync.WaitGroup

       for pb.Next() {
          wg.Add(1)
          go func() {
             attVal := "some-random-value"
             _ = evaluateFeature(gbInstance, attVal)
             wg.Done()
          }()
       }
       wg.Wait()
    })
}

go test -bench=.

b.SetParallelism(change_me)

fatal error: concurrent map read and map write