LND Accounts: Improve error message for insufficient funds

[Liongrass]

Expected behavior

I am using litd with LND Accounts. I have a balance and am trying to pay an invoice for an amount larger than that.

I expect the lncli payinvoice request to fail with an error along the lines of:

Insufficient amount. Invoice of Y sats is larger than balance of X sats

Actual behavior

Instead, I get the following error message

[lncli] rpc error: code = Unknown desc = no request values found for request: 29618

I believe this error message is potentially confusing and lead people to believe they are encountering a complex issue or bug.

System information

litd version 0.14.0-alpha commit=v0.14.0-alpha-dirty