mget add parameter check

[631086083]

when we use a mget command with no keys, it will use resp"*1\r\n$4\r\nmget\r\n" and the redis will return "ERR wrong number of arguments for 'mget' command", some redis proxy will directly close the connection after receiving this illegal command.

Can we add a little check at the client level to reduce this predictable error(same as redis proxy).