[feature]: confusing error messages with lncli closechannel

[AndySchroder]

I tried to close a channel with

lncli closechannel

and I got

[lncli] rpc error: code = Unknown desc = unable to process close msg: transaction rejected by the mempool because of low fees: mempool min fee not met

I'm left thinking the channel still has not negotiated a fee with the peer. This channel happens to be with CLN and so I look at CLN and it does say that the channel is still trying to negotiate a fee.

Then I try to close again with a higher fee

lncli closechannel --sat_per_vbyte 5

and I get the error

[lncli] rpc error: code = Unknown desc = unable to gracefully close channel while peer is offline (try force closing it instead): channel link not found

I then try to connect to the peer again, but I get

[lncli] rpc error: code = Unknown desc = already connected to peer:

after a long time, I find out with lncli pendingchannels that a cooperatively close transaction has already been created (and both LND and CLN had confusing error messages). After a few minutes, LND re-tried broadcasting the transaction and it was accepted into the mempool.

So, I actually need to use lncli wallet bumpfee instead to get the channel to close.

It would be good if the error message when mempool min fee not met condition happens will say that it did actually cooperatively close but the transaction still has not been accepted into the mempool. Also, if a channel is already closed, say that it is closed if you try re-close it instead of saying the peer is offline and I should try to force close.