Docs: omitting parameter that has a default value gives an error message, rather than using the default

[microlancer]

Background

When running lncli updatechanpolicy the time_lock_delta parameter has a "default: 0" according to the --help documentation. However, omitting it results in an error saying time_lock_delta is missing.

Your environment

• lnd v0.12.0-beta
• Linux debian 4.9.0-12-amd64 Fix name typo in README #1 SMP Debian 4.9.210-1+deb9u1 (2020-06-07) x86_64 Linux
• bitcoind

Steps to reproduce

# lncli updatechanpolicy --help
NAME:
   lncli updatechanpolicy - Update the channel policy for all channels, or a single channel.

USAGE:
   lncli updatechanpolicy [command options] base_fee_msat fee_rate time_lock_delta [--max_htlc_msat=N] [channel_point]

CATEGORY:
   Channels

DESCRIPTION:

  Updates the channel policy for all channels, or just a particular channel
  identified by its channel point. The update will be committed, and
  broadcast to the rest of the network within the next batch.
  Channel points are encoded as: funding_txid:output_index

OPTIONS:
   --base_fee_msat value    the base fee in milli-satoshis that will be charged for each forwarded HTLC, regardless of payment size (default: 0)
   --fee_rate value         the fee rate that will be charged proportionally based on the value of each forwarded HTLC, the lowest possible rate is 0 with a granularity of 0.000001 (millionths)
   --time_lock_delta value  the CLTV delta that will be applied to all forwarded HTLCs (default: 0)
   --min_htlc_msat value    if set, the min HTLC size that will be applied to all forwarded HTLCs. If unset, the min HTLC is left unchanged. (default: 0)
   --max_htlc_msat value    if set, the max HTLC size that will be applied to all forwarded HTLCs. If unset, the max HTLC is left unchanged. (default: 0)
   --chan_point value       The channel whose fee policy should be updated, if nil the policies for all channels will be updated. Takes the form of: txid:output_index

bash-5.0# lncli updatechanpolicy --base_fee_msat 1000 --fee_rate 0.000001
[lncli] time_lock_delta argument missing

Expected behaviour

Command should succeed (or we just need to update the documentation?)

Actual behaviour

Command fails

[microlancer]

Per the USAGE line in the help, it looks like the three parameters base_fee_msat, fee_rate, and time_lock_delta are all required. So I think the fix for this issue would be to simply remove the "(default: 0)" because I'm not sure how/when that default would end up being used since a value must be supplied.

[guggero]

Closing as duplicate of #1523.