BUG:No etherbase configured

[lochjin]

Errors will be reported when external signer are used:
./geth --signer=clef.ipc --miner.etherbase=0x... ...

[rjl493456442]

@holiman I think the root cause it once the externalSigner is enabled, all local signers are disabled

// For now, we're using EITHER external signer OR local signers.
// If/when we implement some form of lockfile for USB and keystore wallets,
// we can have both, but it's very confusing for the user to see the same
// accounts in both externally and locally, plus very racey.

However, we use the keystore as the fallback in lots of places, e.g. in this PR, the default etherbase
is the first account in keystore. But apparently this assumption is not held anymore https://github.com/ethereum/go-ethereum/blob/master/cmd/utils/flags.go#L1760

I think we should either:

• support resolving the first account from the external signer
• remove the support for resolving the "first account" as the etherbase

What's your opinion?

[karalabe]

My vote is that we should start cleaning up notions of account[0] everywhere because it's a magical cosntruct that can be unexpected. Since signing requires a lot of infra nowadays, having to explicitly set etherbase seems like one more step out of many, so not much more effort but a lot more clarity.

[rjl493456442]

@lochjin Can you please try out this alternative fix? #26413

[lochjin]

@lochjin Can you please try out this alternative fix? #26413
Okay, I'll try

[lochjin]

@lochjin Can you please try out this alternative fix? #26413

@rjl493456442 After testing, it is confirmed that #26413 can work very correctly