[Engine] Code steps don't support optional chaining (?.) — no clear error

[ameet]

Component

Flow engine — code step runtime

What's wrong?

Code steps silently fail or throw cryptic errors when using JavaScript optional chaining (?.), which has been standard since ES2020 (Node 14+, 2020).

Description

Any code step using foo?.bar or arr?.[0] either:

• Fails silently (returns undefined where it shouldn't)
• Throws an unhelpful syntax error with no mention of optional chaining

The correct pattern is (foo || {}).bar or (arr || [])[0], but every AI coding agent (Claude, GPT, Copilot) generates ?. by default since it's been standard JS for 6 years.

Scale of impact: We had to purge ?. from 69 flows in a single session and now maintain a regression test (brittleness_regression.py) that scans all code steps for ?. usage to prevent reintroduction.

How we discovered this

Flows that worked in local Node testing broke when executed via one flow execute. Root cause was ?. in code steps. Commit 44129c2 documents the mass fix across multiple flows.

Examples

Fails:

const data = $.steps.enrichment?.output?.company;

Works (our workaround):

const data = (($.steps.enrichment || {}).output || {}).company;

Suggested fix

Either:

1. Support optional chaining — upgrade the code step runtime to a modern JS engine/parser
2. Clear error message — if ?. is detected, throw: "Optional chaining (?.) is not supported in code steps. Use (x || {}).y instead."
3. Lint at load time — one flow validate could flag ?. before execution

Option 1 is ideal. Option 2 would save hours of debugging. We currently handle this with option 3 via a custom script.

Source

• MDN: Optional chaining — standard since ES2020
• Our workaround: brittleness_regression.py scans 372 code steps across 88 flows

[moekatib]

Verified working in the current engine (v1.22.x). Code steps run via AsyncFunction directly with no source rewriting, so any modern JS syntax — including optional chaining (?.) and nullish coalescing (??) — works natively.

Repro confirming it works:

{
  "id": "use",
  "type": "code",
  "code": { "source": "const v = $.steps.make.output?.a?.b?.c; return { v };" }
}

Runs cleanly and returns { v: 'hello' }. If you hit a case where ?. actually fails, please reopen with a flow + Node version and we'll dig in.