fix(runtime): define js_node_system_error_value (unbreak cargo-test link)

[proggeramlug]

Summary

main's cargo-test is failing with a linker error, unrelated to any one feature:

/usr/bin/ld: ... libperry_ext_http.a(perry_ffi...): in function `perry_ffi::error::system_error_value':
undefined reference to `js_node_system_error_value'
collect2: error: ld returned 1 exit status
Error: Linking failed

Root cause

PR #5078 (1c9e3c6, "node:http client transport errors → real coded Error") added an extern declaration for js_node_system_error_value in perry-ffi/src/error.rs and a caller (system_error_value() → perry-ext-http's client_events.rs), but the runtime #[no_mangle] definition was never shipped. Any program/test that links perry-ext-http therefore fails at link time. This takes down cargo-test — e.g. issue_4903_listen_callback_deferred's late_listening_listener_fires and listen_callback_is_deferred_and_this_bound.

Fix

Define js_node_system_error_value in perry-runtime/src/error.rs, mirroring the sibling js_error_value_with_code:

• Build the Error from the message.
• Register .code / .syscall / .errno into the message-keyed side tables that the existing object::field_get_set getters already read back (register_error_code_pub / register_error_syscall / register_error_errno — the same mechanism fs/dns/process errors use).
• code/syscall are interned to &'static str (reusing intern_error_code).
• A #[used] anchor pins the symbol against the auto-optimize LTO dead-strip, matching the sibling KEEP_JS_ERROR_VALUE_WITH_CODE.

No behavior change beyond making the already-intended system_error_value path link and produce a Node-shaped system error (.message/.code/.syscall/.errno).

Verification

• cargo build -p perry-runtime -p perry-stdlib -p perry — clean.
• cargo test -p perry --test issue_4903_listen_callback_deferred — 2 passed; 0 failed (both previously failed at the link step).

Context

Surfaced while babysitting CI on #5118 (perry/ui toggleSetState); the failure was unrelated to that PR. This is the focused fix for the main regression.

https://claude.ai/code/session_01HKXzNHuniuu33SAUrLSN2f

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Generated by Claude Code

Summary by CodeRabbit

• New Features
  • Added support for Node.js-compatible system errors with detailed error context, including message, code, syscall identifier, and errno value for improved error handling and debugging.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 784df9bb-95a1-454e-a083-f91eaf6086b4

📥 Commits

Reviewing files that changed from the base of the PR and between c970fc5 and cf6b805.

📒 Files selected for processing (1)

• crates/perry-runtime/src/error.rs

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📝 Walkthrough

Walkthrough

Adds js_node_system_error_value, a #[no_mangle] FFI function in crates/perry-runtime/src/error.rs that constructs a Node-style system Error with .message, .code, .syscall, and .errno fields from raw UTF-8 byte slices, then returns a NaN-boxed pointer. A #[used] keepalive static prevents the symbol from being dead-stripped by LTO.

Changes

Node System Error FFI Export

Layer / File(s)	Summary
js_node_system_error_value implementation and LTO keepalive crates/perry-runtime/src/error.rs	Adds js_node_system_error_value which decodes UTF-8 byte slices for message, code, and syscall, interns the strings, registers .code, .syscall, and .errno into Perry's Node error side tables, allocates the error via js_error_new_with_message, and returns a NaN-boxed f64. Also adds KEEP_JS_NODE_SYSTEM_ERROR_VALUE, a #[used] static pointing to the new symbol to prevent LTO dead-stripping.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• PerryTS/perry#5112: Modifies the same error.rs module, removing js_node_system_error_value in favor of new stack/prepareStackTrace CallSite logic — directly overlapping with this addition.
• PerryTS/perry#5078: Consumes the js_node_system_error_value FFI entry point added here via perry_ffi::system_error_value to build coded system Error objects in the HTTP transport layer.

Poem

🐇 A syscall went awry, a code was assigned,
With .errno and .message perfectly aligned.
I boxed it in NaN, snug and secure,
Then anchored the symbol — LTO won't lure!
Hop hop, the error is ready to throw~ 🎉

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: defining the missing FFI function js_node_system_error_value to fix a linker error in cargo-test.
Description check	✅ Passed	The description is comprehensive and well-structured, covering summary, root cause analysis, detailed fix explanation, verification steps, and context. It aligns well with the template requirements.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/fix-js-node-system-error-value

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