Rebalancing Errors: "Unkown (sic) Error"

[jblachly]

Describe the problem/bug

Attempts at rebalancing channels in topology square (from new LN+ swap) failed with "Unkown (sic) Error". Manually checking the channels, there was no fee error or reason they shouldn't route. Ultimately, a re-attempt succeeded, even though the UI still displayed "Unkown Error". Finally, once the UI has shown "Unkown Error" triggered by a rebalance attempt that ostensibly failed, I was never able to ge tthe UI to respond to a re-attempt (i.e. with the "processing" icon with button press) without logging out and logging back in; the frontend app state was in an inconsistent state, and all future rebalance attempts (even with different nodes and parameters) yielded an instant "Unkown Error" message toast.

Your environment

• Version of ThunderHub: ThunderHub 0.12.31

• Deployment method: Source to empty linux VM

• Other relevant environment details: LND running on separate VM; macaroon and certificate in thubConfig.yaml

To Reproduce Steps to reproduce the behavior:

1. Go to Rebalance page
2. Select appropriate incoming and outgoing channels from a brand new (i.e. zero or no existing flow) LN+ swap (in my case topology was square; all fees were 1 base, 1 ppm)
3. Keep max fee/fee rate defaults of 10 and 100 ppm
4. Set target amount to <= 50% of channel capacity
5. Leave 'avoid nodes' and 'max time' empty (defaults)
6. Click Rebalance

Expected behavior I expect error messages to accurately reflect what the LND backend is returning

I also expect to be able to reattempt the same or a different rebalance without logging out and logging back in.

As a sidenote, "Unknown" is mispelled.

Actual behavior Described in synopsis at top

Screenshots/Links Relevant Logs from this time: (because I'm not yet sure which information is sensitive, I've obfuscated some ids)

2021-11-05 12:03:45.591 [WRN] CRTR: Channel 769... has zero cltv delta
2021-11-05 12:03:46.316 [WRN] CRTR: Channel 680... has zero cltv delta
2021-11-05 12:03:48.406 [WRN] CRTR: Channel 714... has zero cltv delta
2021-11-05 12:03:55.017 [WRN] CRTR: Attempt 1002 for payment (id redacted 7035...) failed: TemporaryChannelFailure(update=(*lnwire.ChannelUpdate)(0xc00462...)({
 Signature: (lnwire.Sig) (len=64 cap=64) {
  00000000  f5 da 2d 84 dc 3d ec 96  fb 2e 1c 96 87 16 74 68  |..-..=........th|
  00000010  ca 99 db 5c 37 37 dd 75  35 ac e0 e1 a8 01 12 b7  |...\77.u5.......|
  00000020  36 90 d8 81 9c 97 47 a5  11 79 78 55 89 78 98 2a  |6.....G..yxU.x.*|
  00000030  ab 75 54 13 a4 37 4d 27  c6 22 87 43 d3 25 eb ba  |.uT..7M'.".C.%..|
 },
 ChainHash: (chainhash.Hash) (len=32 cap=32) 000000000019d6689................................2b3f1b60a8ce26f,
 ShortChannelID: (lnwire.ShortChannelID) XXXXXX:YYY:0,
 Timestamp: (uint32) 1636056377,
 MessageFlags: (lnwire.ChanUpdateMsgFlags) 00000001,
 ChannelFlags: (lnwire.ChanUpdateChanFlags) 00000001,
 TimeLockDelta: (uint16) 40,
 HtlcMinimumMsat: (lnwire.MilliSatoshi) 1000 mSAT,
 BaseFee: (uint32) 0,
 FeeRate: (uint32) 0,
 HtlcMaximumMsat: (lnwire.MilliSatoshi) 495000000 mSAT,
 ExtraOpaqueData: (lnwire.ExtraOpaqueData) {
 }
})
)@3
2021-11-05 12:03:55.767 [WRN] CRTR: Channel 769... has zero cltv delta
2021-11-05 12:03:58.168 [WRN] CRTR: Attempt 1003 for payment (id redacted 69f1...)
80209 failed: TemporaryChannelFailure(update=(*lnwire.ChannelUpdate)(0xc00417...)({
 Signature: (lnwire.Sig) (len=64 cap=64) {
  00000000  9f 52 30 7c e5 38 0a 38  7a 7c ba d9 45 f5 5e 8d  |.R0|.8.8z|..E.^.|
  00000010  3a fe 3b 73 93 9f fa b8  33 3f 92 d0 20 09 08 a0  |:.;s....3?.. ...|
  00000020  2e 21 81 f9 29 7e 90 5a  69 3b d0 a6 94 fb 8c 8d  |.!..)~.Zi;......|
  00000030  db 04 71 8e 1b 94 59 8c  7f a6 8f 50 23 c7 d1 31  |..q...Y....P#..1|
 },
 ChainHash: (chainhash.Hash) (len=32 cap=32) 000000000019d6689c085...............................1b60a8ce26f,
 ShortChannelID: (lnwire.ShortChannelID) AAAAAA:BBBB:0,
 Timestamp: (uint32) 1636082946,
 MessageFlags: (lnwire.ChanUpdateMsgFlags) 00000001,
 ChannelFlags: (lnwire.ChanUpdateChanFlags) 00000001,
 TimeLockDelta: (uint16) 40,
 HtlcMinimumMsat: (lnwire.MilliSatoshi) 1000 mSAT,
 BaseFee: (uint32) 1000,
 FeeRate: (uint32) 1,
 HtlcMaximumMsat: (lnwire.MilliSatoshi) 2475000000 mSAT,
 ExtraOpaqueData: (lnwire.ExtraOpaqueData) {
 }
})
)@2

with several more repetitions of the TemporaryChannelFailure followed by:

2021-11-05 12:04:20.110 [WRN] CRTR: Attempt 1005 for payment (id redacted 82e...) failed: IncorrectOrUnknownPaymentDetails(amt=219439000 mSAT, height=708314)@5
2021-11-05 12:04:20.116 [INF] CRTR: Payment (id redacted 82e...) failed: final_outcome=incorrect_payment_details, raw_err=IncorrectOrUnknownPaymentDetails(amt=219439000 mSAT, height=708314)@5

and again many more repetitions as "Attempt 1006", "1007" etc. each with different amounts (I suppose breaking up the large payment?)

Additional context None