Don't panic on some AuRa transactions in the past

[mandrigin]

Example request that crashed the RPC method handler on Gnosis Chain mainnet.

{
    "id": "1",
    "jsonrpc": "2.0",
    "method": "debug_traceBlockByNumber",
    "params": [
        "0x8a1f76",
        {
            "tracer": "callTracer"
        }
    ]
}

[yperbasis]

Does it fix Issue #6759?

[mandrigin]

@yperbasis yep, we had exactly that

RPC method debug_traceBlockByNumber crashed: abi: attempting to unmarshall an empty string while arguments are expected