Channel queries: failure to decode empty array of timestamps

[sstone]

Issue and Steps to Reproduce

c-lighting fails to decode a reply_channel_range message that includes an optional timestamps TLV with an encoding type set to ZLIB and an empty encoded data buffer, and returns a connection-level error, failing all channels! reason=reply_channel_range 0 timestamps when 0 scids? error, most probably because it tries to decompress an empty or NULL buffer

Imho an empty encoded buffer should decode to an empty list, even if its encoding is set to ZLIB, and I've opened a PR to clarify this (see lightning/bolts#729)

getinfo output

{
   "id": "03daa35dc54f90a5fc7f726d58ad0890281843ce99c9a1680a4065138848a5d1e1",
   "alias": "IRATESPAWN-v0.8.0-60-ge1ef902",
   "color": "03daa3",
   "num_peers": 0,
   "num_pending_channels": 0,
   "num_active_channels": 0,
   "num_inactive_channels": 0,
   "address": [],
   "binding": [
      {
         "type": "ipv4",
         "address": "127.0.0.1",
         "port": 19736
      }
   ],
   "version": "v0.8.0-60-ge1ef902",
   "blockheight": 1662433,
   "network": "testnet",
   "msatoshi_fees_collected": 0,
   "fees_collected_msat": "0msat",
   "lightning-dir": "/home/fabrice/.lightning/testnet"
}

[sstone]

I agree now with @cdecker that it was rather a pb on our side