enable custom go linter in CI

[hopeyen]

(disclaimer: I'm not usually this talkative with PR comments, being unusual because I'm new and trying to become familiar with things)

This PR contains minor refactoring to make the linter happy

For the custom go run ./linters ./..., the only complain was

 ✗ go run ./linters ./...
.../nitro/eigenda/eigenda.go:36:2: field eigenda.EigenDAConfig.Enable not used
.../nitro/eigenda/eigenda.go:37:2: field eigenda.EigenDAConfig.Rpc not used
exit status 3

As a new gopher, I've tried using unused: ignore-field in .golang.ci.yml, adding used:"true" as part of field definitions, //nolint:unused to disable check for the config struct, modifying the structinit.go analyzer, but nothing worked until I made a dumb initializer for the struct 🤦 If I'm missing anything obvious, please let me know and I will make smarter changes.
So then, reviewing that EigenDAConfig is only used for initializing EigenDAClient, I think it makes sense to have arbnode pass in the config struct instead of only the RPC field. If we want more granular control of client initailization in the future, this change is probably in the right direction. Also included an additional/duplicate check for Enable to make linter happy; I think we can delete this check in arbnode, but I'm nervous about safety in golang

golangci-lint

a couple of failures there, change explanations:

all files got go fmted.
go sec

arbnode/dataposter/data_poster.go:223:23: G402: TLS InsecureSkipVerify may be true. (gosec)
-> #nosec moved to group config (https://github.com/securego/gosec/issues/278#issuecomment-461251791)

^ this is okay when updated local to 1.59.1

go critic

eigenda/decoding.go:119:17: appendAssign: append result not assigned to the same slice (gocritic)
        encodedData := append(codecBlobHeader, rawDataPadded...)
                       ^
->  keep using append by assign it back to the original slice
eigenda/proxy.go:18:28: captLocal: `RPCUrl' should not be capitalized (gocritic)
func NewEigenDAProxyClient(RPCUrl string) *EigenDAProxyClient {
                           ^
-> replace `RPCUrl` with `rpcUrl`
arbnode/sequencer_inbox.go:178:23: unslice: could simplify calldata[:] to calldata (gocritic)
                data = append(data, calldata[:]...)
                                    ^
-> simplified

errorlint

eigenda/proxy.go:143:66: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors (errorlint)
                return nil, fmt.Errorf("failed to construct http request: %e", err)
                                                            ^
-> %e to %w                                             

govet

eigenda/types.go:257:30: nilness: tautological condition: non-nil != nil (govet)
        if &e.BlobVerificationProof != nil {
                                    ^
eigenda/types.go:259:45: nilness: tautological condition: non-nil != nil (govet)
                if &e.BlobVerificationProof.BatchMetadata != nil {
                                                          ^
-> always tautological since taking the address of a struct field will always return a non-nil pointer even if the field itself is a nil pointer or has a zero value.
-> added IsEmpty helpers for structs and use that for the checks

🤞 let's see if CI will pass

[hopeyen]

all lint tests passed, only thing failing is docker build (local rpc not working)

resolves #7

[epociask]

Just one comment - otherwise LGTM

[epociask]

why panic versus bubbling error up -- also given that there's a precursor check performed within the caller for the Enable flag we can probably get rid of this

[hopeyen]

Agreed, updated to bubbling error up.

This check exists purely because of the linter's complain that Enable hasn't been used even with the caller's check, more detailed reasoning is in the PR comments, happy to learn about alternatives 🤔

[epociask]

keep meaning to refactor this type conversions - ty! 🙏🏻

[epociask]

we can prolly do without these comments

[hopeyen]

cool! I removed the comments but added a constant SequencerMsgOffset to hold 41 for clearer usage

[epociask]

LGTM