incompatibility with lighthouse for certain pre-capella post-merge blocks

[invis-bitfly]

Context

According to the lighthouse guys this happens because Erigon returns a [] instead of a null for withdrawals. I was able to temporarily fix this by making lighthouse allow empty arrays for that region of blocks. (also confirmed that it works correctly with reth+lighthouse)

System information

• Erigon version: erigon version 2.60.5-ea49defc
• OS & Version: Linux
• Commit hash: ea49defc
• Erigon Command (with flags/config): nothing relevant set
• Consensus Layer: lighthouse v5.2.1
• Consensus Layer Command (with flags/config):

lighthouse_v5.2.1
  beacon_node
  --network=mainnet
  --reconstruct-historic-states
  --slots-per-restore-point=128
  --historic-state-cache-size=64
  --genesis-backfill
  --prune-payloads=false
  --prune-blobs=false
  --disable-backfill-rate-limiting
  …

• Chain/Network: mainnet

Expected behaviour

curl http://127.0.0.1:{lighthouse_port}/eth/v2/beacon/blocks/6176903 | jq

{
  "version": "bellatrix",
  "execution_optimistic": false,
  "finalized": true,
  "data": {
    "message": {
      "slot": "6176903",
      "proposer_index": "496013",
      "parent_root": "0x74ff8300772365ecaa41cae7a2768c705610ff6e638dc8471515d118a3315288",
      "state_root": "0x67c2def4747bae0fbfa1adbc2f8b02999916c31caf6812454fc40b8910adbec9",
      "body": {
        "randao_reveal": "0x99acb7741bc0b85eb510bc845d6a4f9c5a49b4a28c88ab03386d96a70ea0708f67b6d382b2090b59feabdeb4a2b2292b01e609f9aa227f955be344a07d936044c5613c9da20ab8f9c5177256a067f4771e11d0ef576c3be4346491e9f4a3acd5",
        "eth1_data": {
          "deposit_root": "0xe3ae098c31e93e87682a2415a2b22a19c6e3e7cd5425f9defc7156d958340a66",
          "deposit_count": "580121",
          "block_hash": "0x6405bc1fbd2298565b79b8e26d39297e9c3b457c8dfb72ab37ef35250f1c7cea"
        },
        "graffiti": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "proposer_slashings": [],
        "attester_slashings": [],
…

Actual behaviour

curl http://127.0.0.1:{lighthouse_port}/eth/v2/beacon/blocks/6176903 | jq

{
  "code": 500,
  "message": "UNHANDLED_ERROR: ExecutionLayerErrorPayloadReconstruction(0xa93514c91306a086c40bba2282c1dc4f8ba61fb062f7f596d2d7412e514a601f, InvalidPayloadBody(\"block 0xa935…601f is merge but payload body has withdrawals\"))",
  "stacktraces": []
}

Steps to reproduce the behaviour

1. configure lighthouse & erigon
2. request block at slot 6176903 from lighthouse