* Reject duplicate sprout nullifiers in the state
* Improve docs and error messages
* Clarify "must be present" assert logs
* Move nullifier checks to their own module
Also:
* make non-finalized nullifier checks and errors generic over
sprout, sapling, and orchard
* create and update module and function documentation
* Fix a block type name in docs
* Move state assertions or skip them during tests
These changes enable state testing, while still asserting in production.
* Add sprout duplicate nullifier tests
* Improve comments
* Set value balance to 0 to pass future chain value pool checks
* Test finalized state in sprout nullifier accept test
* Replace assert with expect
* Improve assertion messages
* Skip invalid legacy chain check test cases
Add proptest seeds for the failing test.
And improve some unclear documentation.
* Fix the legacy chain test blocks order
Also fix unclear documentation that might have led to this bug.
teor