Lodestar can not parse non-hex string validator_index in getStateValidatorBalances

[Alleysira]

Hello Lodestar team,

I’ve encountered a potential inconsistency with how Lodestar handles validator_balances requests.

According to the beacon-API specification, the id parameter can be a validator index represented as a string (e.g., "22710") or a hex-encoded public key. However, when making the following request:

curl -X GET http://localhost:4000/eth/v1/beacon/states/head/validator_balances?id=22710

The differential testing results show that only lodestar return error

{"code":500,"message":"hex string length 5 must be multiple of 2"} # lodestar
{"data": [], "execution_optimistic": false, "finalized": false} # prysm
{"data": [], "execution_optimistic": false, "finalized": false} # lighthouse
{"data": [], "execution_optimistic": false, "finalized": false} # teku
{"data": [], "execution_optimistic": false, "finalized": false} # nimbus
{"data": [], "execution_optimistic": false, "finalized": false} # grandine

Schema:

{
  "name": "id",
  "description": "Either hex encoded public key (any bytes48 with 0x prefix) or validator index",
  "in": "query",
  "required": false,
  "schema": {
    "type": "array",
    "maxItems": 64,
    "uniqueItems": true,
    "items": {
      "description": "Either hex encoded public key (any bytes48 with 0x prefix) or validator index",
      "type": "string"
    }
  }
}

Related code implementation in lodestar:

lodestar/packages/beacon-node/src/api/impl/beacon/state/index.ts

Lines 203 to 212 in 33ca095

	if (typeof id === "number") {
	if (state.validators.length <= id) {
	continue;
	}
	balances.push({index: id, balance: state.balances.get(id)});
	} else {
	const index = headState.epochCtx.pubkey2index.get(fromHex(id));
	if (index != null && index <= state.validators.length) {
	balances.push({index, balance: state.balances.get(index)});
	}

Thanks for your time!