Logging (pathfind): Don't log [WRN] CRTR: Channel x has zero cltv delta

[C-Otto]

Background

Inspired by C-Otto/rebalance-lnd#241.

As part of pathfinding, lnd might encounter edges that have a policy specifying a zero CLTV delta (possibly because of no/outdated gossip?). Every time an edge like this is used in the pathfinding code, a warning is logged:

lnd/routing/pathfind.go

Line 705 in 290b78e

log.Warnf("Channel %v has zero cltv delta",

For nodes that query a lot of routes (for example when running rebalance-lnd), countless warnings are logged. These warnings don't seem to serve a proper purpose, as the user cannot do anything about it, and in my experience this also didn't cause any issues.

Your environment

• lnd-0.14.1-beta
• Linux server 5.10.0-8-amd64 #​1 SMP Debian 5.10.46-4 (2021-08-03) x86_64 GNU/Linux
• bitcoind v22

Steps to reproduce

Run QueryRoutes a few times.

Expected behaviour

Warning from issue title is not logged.

Actual behaviour

Warning from issue title is logged quite often.

[ErikEk]

I can fix it if we want this change.

[sloorush]

Hey!
I am interested in working on this issue, but could someone please explain what exactly needs to be done as PR #6242 was not accepted, which removes the check and the log.

[ziggie1984]

Closing with #7267