TypeError stack-trace output diverges from Node — Perry's 'Uncaught exception:' prefix + missing file:line header (regression from v0.5.702 #596)

[proggeramlug]

Summary

test_issue_462_nullish_property_access.ts and test_issue_510_primitive_method_typeerror.ts both diverge from Node's parity output not because Perry's behavior is wrong, but because Perry's uncaught-exception format doesn't match Node's. Both tests trigger a real TypeError and Perry correctly throws it; the test's UNREACHABLE line correctly never prints. The remaining failure is purely the framing.

This regressed in v0.5.702 (#596 — TypeError throw helpers route through js_throw). The print_uncaught function in crates/perry-runtime/src/exception.rs:159+ was modified at that point to emit a single Uncaught exception: <Name>: <message> line plus the stack string.

Diff (test_issue_462)

Node:
  about to throw — last line of stdout
  file:///Users/.../test_issue_462_nullish_property_access.ts:33
  console.log(undef.foo);
                    ^

  TypeError: Cannot read properties of undefined (reading 'foo')
      at file:///.../test_issue_462_nullish_property_access.ts:33:19
      at ModuleJob.run (node:internal/modules/esm/module_job:430:25)
      ...

Perry:
  about to throw — last line of stdout
  Uncaught exception: TypeError: Cannot read properties of undefined (reading 'foo')
  TypeError: Cannot read properties of undefined (reading 'foo')
      at <anonymous>

Three concrete differences:

1. Perry has the Uncaught exception: prefix; Node does not.
2. Perry omits the file:line "header" block (file URL, source-line, caret, blank).
3. Stack frames differ — Perry's at <anonymous> vs Node's at <file>:<line>:<col> + module-job frames.

Symptom shared by

• test_issue_462_nullish_property_access
• test_issue_510_primitive_method_typeerror

(any future test that intentionally throws + lets it escape will hit the same format divergence)

Reproducer

const x: any = undefined;
console.log(x.foo);  // throws TypeError

node --experimental-strip-types repro.ts vs perry repro.ts && ./out produces the diff above.

Suggested approach

If matching Node byte-for-byte is the goal: extend print_uncaught in exception.rs to emit a Node-shaped header. Source-line + caret requires reading the original source text + columns, which the runtime doesn't currently retain at throw time — would need an HIR-side annotation that flows the source-text snippet for the throwing site to the runtime.

If matching Node exactly is unrealistic (Perry's stack frames have a different shape — no module-job, no async-job machinery), an alternative: keep the current Perry format but add it to the parity harness's known-divergence allowlist, so these tests don't show up as failures every sweep.

Environment

• Perry 0.5.712
• macOS arm64 / 26.4
• Surfaced by scripts/release_sweep.sh tier 2; regression point: v0.5.702 (Sync throw inside async fn body escapes outer try/catch around await #596)

[proggeramlug]

Closed in v0.5.719 with two coordinated changes:

1. Format: crates/perry-runtime/src/exception.rs::print_uncaught no longer emits the duplicate Uncaught exception: prefix line. The stack string already starts with <Name>: <msg> per Error.stack convention, so the prefix is redundant. Output now reads TypeError: <msg> / at <frame> matching Node's leading-line format.

2. Acceptance via known_failures.json: full Node byte-for-byte parity (file:line header, source line + caret, file-URL stack frames, module-job machinery, Node.js version epilogue) requires source-text retention through the runtime — out of scope for this fix. test-parity/known_failures.json gets new entries for test_issue_462_nullish_property_access + test_issue_510_primitive_method_typeerror referencing TypeError stack-trace output diverges from Node — Perry's 'Uncaught exception:' prefix + missing file:line header (regression from v0.5.702 #596) #616.

Cleanup: removed three stale entries (test_edge_destructuring, test_edge_objects_records, test_gap_object_methods) closed in v0.5.713 — those match Node byte-for-byte now.