IAsyncEnumerator 项变为空

如何解决IAsyncEnumerator 项变为空

在使用枚举器迭代我的 ReliableDictionary 时，“Current.Value”返回 null，因为“totalLength += val.Length;”行抛出 NullPointerException。 这怎么可能？

public async Task RemoveItemsPeriodically()
{
    try
    {
        var totalLength = 0;
        var dict= await this.stateManager.GetorAddAsync<IReliableDictionary<string,Item>>("dict");
        using (ITransaction tx = this.stateManager.CreateTransaction())
        {
            IAsyncEnumerable<keyvaluePair<string,Item>> asyncEnumerable = await dict.CreateEnumerableAsync(tx);
            List<string> removeKeys= new List<string>();
            using (IAsyncEnumerator<keyvaluePair<string,Item>> asyncEnumerator = asyncEnumerable.GetAsyncEnumerator())
            {
                while (await asyncEnumerator.MoveNextAsync(CancellationToken.None))
                {
                    if (asyncEnumerator == null || asyncEnumerator.Current.Value == null)
                    {
                        Log();
                    }
                    else
                    {
                        var keyvalue = asyncEnumerator.Current;
                        var key = keyvalue.Key;
                        var val= keyvalue.Value;
                        totalLength += val.Length;
                        if (this.checkToDelete(item.DeleteValue))
                        {
                            removeKeys.Add(key);
                        }
                    }
                }

                foreach (string keyToRemove in removeKeys)
                {
                    dict= await this.stateManager.GetorAddAsync<IReliableDictionary<string,Item>>("dict");
                    await dict.TryRemoveAsync(tx,keyToRemove);
                }
            }

            await tx.CommitAsync();
        }
    }
}