fix(gateway): return error instead of nil for unknown filter in EthGetFilterLogs

[sudo-shashank]

Related Issues

ChainSafe/forest#6580

Proposed Changes

• Return ErrFilterNotFound instead of nil when filter not found in EthGetFilterLogs for both v1 and v2 gateway proxies.

Additional Info

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title conforms with contribution conventions
• Update CHANGELOG.md or signal that this change does not need it per contribution conventions
• New features have usage guidelines and / or documentation updates in
  • Lotus Documentation
  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green

[rvagg]

@sudo-shashank have you tried running this and does it get you the results you want? I haven't looked widely and am not sure if error code matters here at all but quicknode's example runner gives me:

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32000,
    "message": "filter not found"
  }
}

[sudo-shashank]

@sudo-shashank have you tried running this and does it get you the results you want? I haven't looked widely and am not sure if error code matters here at all but quicknode's example runner gives me:

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32000,
    "message": "filter not found"
  }
}

@rvagg via lotus gateway we don't get filter not found error message if filter id is not found for Filecoin.EthGetFilterLogs, it currently returns nil.
This error is expected and return correctly only for Filecoin.EthGetFilterChanges as implemented here

[rvagg]

with PR (and therefore commit msg) and changelog tweaks applied