fix: missing code read in state write

[Nashtare]

We're currently erroring when missing an entry in the Hash2Code map. The access being done upon state_read in a state write, I'm wondering whether we should always expect the client to provide necessary information, or if we should allow missing entries.

In the current state of things, block 1034, txn 0 (0xcfaf63b718a548069b856e8ff6b27ad69c3e8ca84ae2ab6ae67c545ecf0b642c) is failing to parse at the decoder stage because we're missing contract bytecode associated to this txn trace:

            "0xd18e94fa1353e8b3b72e64ffc4a64d28a98cdee1": {
              "code_usage": {
                "read": "0x4ab15219b84093c7fd1c51566743820f9383a50b34c3f302b5331f26a89ddc73"
              }
            },

However, the prover does not need it and processes the txn payload fine with the change on this branch. I think Jerigon here knows we can skip the actual bytecode, and hence isn't passing it to the compact witness (@cffls to confirm). In which case we should not bail! when failing to find the mapping bytecode.

Opening as discussion because I'm not clear yet as to what the assumption should be / who's responsability it should be.
Passing the block payload here (note that it's failing to run further ahead)
b1034_dev.json

3.5/N @praetoriansentry

[0xaatif]

I think allow_missing_code should be a parameter to middle, not a property of Hash2Code.

But I don't think we want it at all:

// TODO(Nashtare): https://github.com/0xPolygonZero/zk_evm/issues/...
//                 This is a bug in the zero tracer, which shouldn't be giving us this read at all.
//                 Workaround for now.
if let Some(code) = code.get(hash) {
    batch_contract_code.insert(code)
}

[Nashtare]

But I don't think we want it at all

Don't we want to at least disable this edge case for the native tracer?

[0xaatif]

Don't we want to at least disable this edge case for the native tracer?

Missed this from our Slack discussion :D

Makes sense, let's do, and document this our choice at the call site.

pub struct FatalMissingCode(pub bool);

fn middle(..., fatal_missing_code: FatalMissingCode) {..}

// TODO(Nashtare): https://github.com/0xPolygonZero/zk_evm/issues/...
//                 This is a bug in the zero tracer, which shouldn't be giving us this read at all.
//                 Workaround for now.
match (fatal_missing_code, code.get(hash)) {
    (FatalMissingCode(true), None) => bail!("no code for hash {hash}"),
    (_, Some(it)) => batch_contract_code.insert(code),
    (_, None) => warn!(%hash, "no code for hash"),
}

[0xaatif]

love it!

[0xaatif]

This is my first time realising that native = separate, and compact = jerigon