lnwallet/wallet.go: clarify anchor chan error str

Improve 'ErrReservedValueInvalidated' error string to explain that the
error is triggered by a transaction that would deplete funds reserved for
potential future anchor channel closings (via CPFP)

Add hint that further details can be found in the debug log

Update strings in 'lntest/itest/log_error_whitelist.txt' correspondingly

docs/release-notes/release-notes-0.14.0.md

@@ -33,6 +33,7 @@ you.
 
 * [A new build target itest-race](https://github.com/lightningnetwork/lnd/pull/5542) 
   to help uncover undetected data races with our itests.
+
 * [The itest error whitelist check was removed to reduce the number of failed
   Travis builds](https://github.com/lightningnetwork/lnd/pull/5588).
 
@@ -41,6 +42,12 @@ you.
 * [Outdated warning about unsupported pruning was replaced with clarification that LND **does**
   support pruning](https://github.com/lightningnetwork/lnd/pull/5553)
 
+* [Clarified 'ErrReservedValueInvalidated' error string](https://github.com/lightningnetwork/lnd/pull/5577)
+   to explain that the error is triggered by a transaction that would deplete
+   funds already reserved for potential future anchor channel closings (via
+   CPFP) and that more information (e.g., specific sat amounts) can be found
+   in the debug logs.
+
 # Misc
 
 * The direct use of certain syscalls in packages such as `bbolt` or `lnd`'s own
@@ -54,15 +61,23 @@ you.
 
 * [Unused error check 
   removed](https://github.com/lightningnetwork/lnd/pull/5537).
+
 * [Shorten Pull Request check list by referring to the CI checks that are 
   in place](https://github.com/lightningnetwork/lnd/pull/5545).
+
 * [Added minor fixes to contribution guidelines](https://github.com/lightningnetwork/lnd/pull/5503).
+
 * [Fixed typo in `dest_custom_records` description comment](https://github.com/lightningnetwork/lnd/pull/5541).
+
 * [Bumped version of `github.com/miekg/dns` library to fix a Dependabot
   alert](https://github.com/lightningnetwork/lnd/pull/5576).
+
 * [Fixed timeout flakes in async payment benchmark tests](https://github.com/lightningnetwork/lnd/pull/5579).
+
 * [Fixed a missing import and git tag in the healthcheck package](https://github.com/lightningnetwork/lnd/pull/5582).
+
 * [Fixed a data race in payment unit test](https://github.com/lightningnetwork/lnd/pull/5573).
+
 * [Missing dots in cmd interface](https://github.com/lightningnetwork/lnd/pull/5535).
 
 ## Database
@@ -71,8 +86,8 @@ you.
   code](https://github.com/lightningnetwork/lnd/pull/5547) when using etcd
   backend.
 
-[Optimized payment sequence generation](https://github.com/lightningnetwork/lnd/pull/5514/)
+* [Optimized payment sequence generation](https://github.com/lightningnetwork/lnd/pull/5514/)
-to make LNDs payment throughput (and latency) with better when using etcd.
+  to make LNDs payment throughput (and latency) with better when using etcd.
 
 ## Performance improvements
 
@@ -84,4 +99,5 @@ to make LNDs payment throughput (and latency) with better when using etcd.
 * Martin Habovstiak
 * Zero-1729
 * Oliver Gugger
+* xanoni
 * Yong Yu

lntest/itest/log_error_whitelist.txt

@@ -266,9 +266,9 @@
 <time> [ERR] UTXN: Failed to sweep first-stage HTLC (CLTV-delayed) output <chan_point>
 <time> [ERR] UTXN: Notification chan closed, can't advance output <chan_point>
 <time> [ERR] DISC: Unable to rebroadcast stale announcements: unable to retrieve outgoing channels: channel from self node has no policy
-<time> [ERR] RPCS: [/lnrpc.Lightning/OpenChannel]: reserved wallet balance invalidated
+<time> [ERR] RPCS: [/lnrpc.Lightning/OpenChannel]: reserved wallet balance invalidated: transaction would leave insufficient funds for fee bumping anchor channel closings (see debug log for details)
-<time> [ERR] RPCS: [/lnrpc.Lightning/SendCoins]: reserved wallet balance invalidated
+<time> [ERR] RPCS: [/lnrpc.Lightning/SendCoins]: reserved wallet balance invalidated: transaction would leave insufficient funds for fee bumping anchor channel closings (see debug log for details)
-<time> [ERR] RPCS: unable to open channel to NodeKey(<hex>): reserved wallet balance invalidated
+<time> [ERR] RPCS: unable to open channel to NodeKey(<hex>): reserved wallet balance invalidated: transaction would leave insufficient funds for fee bumping anchor channel closings (see debug log for details)
 <time> [ERR] NANN: Unable to retrieve chan status for Channel(<chan_point>): unable to extract ChannelUpdate
 <time> [ERR] NTFN: Unable to rewind chain from height 1 to height -1: unable to find blockhash for disconnected height=<height>: -8: Block height out of range
 <time> [ERR] RPCS: WS: error writing message: websocket: close sent

lnwallet/wallet.go

@@ -59,7 +59,8 @@ var (
 	// transaction that would take the walletbalance below what we require
 	// to keep around to fee bump our open anchor channels.
 	ErrReservedValueInvalidated = errors.New("reserved wallet balance " +
-		"invalidated")
+		"invalidated: transaction would leave insufficient funds for " +
+		"fee bumping anchor channel closings (see debug log for details)")
 )
 
 // PsbtFundingRequired is a type that implements the error interface and