Block validation failure isn't an error, it's correct rejection of a bad block
from the network. All conditions that lead to block rejection return a simple
boolean.
When a block is rejected, most reasons log at `debug` level. Only `stateRoot`
mismatch shouts a loud, highlighted, multi-line error message with big red
`error` alert.
Historically this was to assist EVM development, because it was more likely to
be a Nimbus EVM bug than a real bad block. But now the EVM is in good shape,
has a large and thorough testsuite, and `stateRoot` mismatch is more likely to
be a real bad block that should be rejected with less fuss.
If there's a genuine EVM bug, we'll still get an alert: Consensus failure will
quickly become obvious, and the block where it happens is easily fetched.
So a big, loud error is no longer useful, and it became a problem during tests.
Recently a few hundred tests were added that trigger it, and now successful
test output is filled with attention-grabbing errors which aren't really errors
or particularly useful.
Since it's not really an error, the original motivation is now backwards, and
other reasons warn at `debug` level, make this like the others.
Signed-off-by: Jamie Lokier <jamie@shareable.org>
a4f92a6543