并非所有代码路径都在c＃Gzip中返回值错误

Question

我为Gzip方法提供了此代码，但它给了我错误，而且我不知道为什么。如果有人愿意帮助消除此错误，我将不胜感激！我从1小时开始寻找解决方案，但找不到任何东西，所以这就是我在这里写的原因。

public async System.Threading.Tasks.Task<byte[]> GZip(byte[] B, bool CM)
    {
        await Task.Delay(10000);
        try
        {
            if (CM)
            {
                byte[] buffer = null;
                using (System.IO.MemoryStream MS = new System.IO.MemoryStream())
                {
                    System.IO.Compression.GZipStream Ziped = new System.IO.Compression.GZipStream(MS, System.IO.Compression.CompressionMode.Compress, true);
                    Ziped.Write(B, 0, B.Length);
                    Ziped.Dispose();
                    MS.Position = 0;
                    buffer = new byte[(System.Convert.ToInt32(MS.Length) + 1) - 1 + 1];
                    MS.Read(buffer, 0, buffer.Length);
                    MS.Dispose();
                }
                return buffer;

            }
            else
            {
                byte[] array = null;
                using (System.IO.MemoryStream MS = new System.IO.MemoryStream(B))
                {
                    System.IO.Compression.GZipStream Ziped = new System.IO.Compression.GZipStream(MS, System.IO.Compression.CompressionMode.Decompress);
                    byte[] buffer = new byte[4 - 1];
                    MS.Position = (MS.Length - 5);
                    MS.Read(buffer, 0, 4);
                    int count = BitConverter.ToInt32(buffer, 0);
                    MS.Position = 0;
                    array = new byte[((count - 1) + 1) - 1 + 1];
                    Ziped.Read(array, 0, count);
                    Ziped.Dispose();
                    MS.Dispose();
                }
                return array;
            }
        }
        catch (Exception)
        {
        }
    }