Ошибка NullPointerException в коде kotlin

Ошибка:

java.lang.NullPointerException: null cannot be cast to non-null type java.util.HashMap<kotlin.String, kotlin.Any?>{ kotlin.collections.TypeAliasesKt.HashMap<kotlin.String, kotlin.Any?> }

Код:

var users = (it.result.value as HashMap<String, Any?>).map {
            var user_list = it.value as HashMap<String, String>
            list_uid.add(it.key)
            return@map User(
                user_list.get("firstName"), user_list.get("lastName"),

                user_list.get("birthday"), user_list.get("country_live")
            )
        }