Log the error, when trying to forward the intercepted HTLC, but the channel is not found

[shaavan]

Resolves #2712

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6e40e5f) 88.80% compared to head (dce514e) 88.66%.
Report is 25 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2726      +/-   ##
==========================================
- Coverage   88.80%   88.66%   -0.15%     
==========================================
  Files         113      113              
  Lines       89170    89370     +200     
  Branches    89170    89370     +200     
==========================================
+ Hits        79188    79236      +48     
- Misses       7729     7882     +153     
+ Partials     2253     2252       -1     

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[shaavan]

Updated from pr2726.01 -> pr2726.02 (diff)
Addressed @TheBlueMatt comments

[TheBlueMatt]

LGTM. No real reason to wait for another review here, it doesn't change the error message/allocation pattern, only adds a new log, which while it is an ERROR level log it is in response to a user action which shouldn't really happen in production except in rare races.