RPC - return null result if requested block not found

[macfarla]

Signed-off-by: Sally MacFarlane macfarla.github@gmail.com

PR description

If block not found, return a Success response with null result, NOT an Error response.

This affects all RPC methods that use AbstractBlockParameterOrBlockHashMethod
including
debug_accountAt, debug_setHead, eth_call, eth_getBlockReceipts, eth_getProof, eth_simulateV1, eth_getBalance, eth_getCode, eth_getStorageAt, eth_getTransactionCount

I've included this as a breaking change in the changelog since it is a change in behavior. However this is what the hive tests expect and it's moving towards being more consistent with other clients.

Fixed Issue(s)

Fixes #9197

Fixes hive tests:

• eth_getBlockReceipts/get-block-receipts-empty
• eth_getBlockReceipts/get-block-receipts-future
• eth_getBlockReceipts/get-block-receipts-not-found

Thanks for sending a pull request! Have you done the following?

• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• spotless: ./gradlew spotlessApply
• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests
• hive tests: Engine or other RPCs modified?

[macfarla]

draft bc this has unfortunately broken these hive tests:
eth_simulateV1/ethSimulate-empty-with-block-num-set-plus1
eth_simulateV1/ethSimulate-make-call-with-future-block

[macfarla]

In Besu we have an abstract class AbstractBlockParameterOrBlockHashMethod that is used by several RPCs - so any RPC that gets a block by block number or hash will have the same error handling behavior. Including:
debug_accountAt, debug_setHead, eth_call, eth_getBlockReceipts, eth_getProof, eth_simulateV1, eth_getBalance, eth_getCode, eth_getStorageAt, eth_getTransactionCount

The spec, and the hive tests, are inconsistent with error handling expectations.

return null if block not found
so there’s hive tests for getBlockReceipts
but fixing those broke hive tests for eth_simulate that use a future block. Is it expected that we would want different behavior here or should eth_simulate also return null if the requested block is not found?
this PR fixes 3 hive tests and breaks 2

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