- Remove unnecessary `Defect` references
- Remove spurious `SerializationError` references
- Remove duplicate `writeValue` template in `keystore.nim`;
same implementation already exists a bit further above in same file.
Some upstream repos still need fixes, but this gets us close enough that
style hints can be enabled by default.
In general, "canonical" spellings are preferred even if they violate
nep-1 - this applies in particular to spec-related stuff like
`genesis_validators_root` which appears throughout the codebase.