fix(rpc): return -32602 error for eth_getLogs with pending block tag

[osr21]

Problem

Closes #426.

When eth_getLogs is called with "fromBlock": "pending" or "toBlock": "pending", Reth resolves "pending" as head + 1 and returns an empty array []. Arc intentionally hides all pending-block state for public RPC nodes, so returning [] silently misleads callers into thinking no logs exist at the current head.

Solution

Add a pending_logs_error guard in NoPendingTransactionsRpcMiddleware::intercept_or_forward that detects "pending" tags in eth_getLogs filter params and returns a -32602 Invalid params error:

{
  "code": -32602,
  "message": "\"pending\" block tag is not supported for eth_getLogs on Arc; use \"latest\" instead"
}

This is consistent with how the middleware handles other pending-block RPCs — rejecting with a structured error rather than returning a misleading empty or null result.

Changes

• crates/evm-node/src/rpc_middleware.rs
  • Added ETH_GET_LOGS_METHOD and PENDING_LOGS_ERROR_CODE constants
  • Added pending_logs_error() helper that parses filter params and checks for pending tags (positional and object-form)
  • Wired the helper into intercept_or_forward, returning an error before the null-response path

Testing

Existing middleware unit tests cover the intercept_or_forward dispatch path. A targeted test for the new guard should be added in a follow-up (the in-module test harness does not yet exercise eth_getLogs params).

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Hi @osr21,

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