This makes for more useful errors. It prints where it was up to in
the guide, but doesn't print the entire JSON it's scanning.
Suggested-by: Christian Decker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This will cause blow ups for v2 multifundchannel attempts with failures,
but allows us to return the expected errors for single-shot
fundchannel attempts.
Error handling is coming, i promise
Ideally we'd 'cure' the error and re-attempt, except that if this was a
bitcoin-backend 'failure to broadcast' then it really needs user
intervention to figure out what's wrong -- it's possible that the
peer successfully broadcast the transaction
We only have output scripts for v1 protocols after the
fundchannel_start/openchannel_init round. We need to add them before
we get into the openchannel_update rounds, however, so we do that here.
