Fix crash in Error.captureStackTrace when stackTraceLimit is nullopt

[robobun]

Fixes a crash (SIGABRT) in Error.captureStackTrace when Error.stackTraceLimit has been deleted or set to a non-number value.

Root Cause

In FormatStackTraceForJS.cpp, line 685 calls .value() on the std::optional<unsigned> returned by globalObject->stackTraceLimit():

size_t stackTraceLimit = globalObject->stackTraceLimit().value();

When Error.stackTraceLimit is set to a non-number (e.g. a string, undefined) or deleted, ErrorConstructor::put / ErrorConstructor::deleteProperty in WebKit sets the internal optional to std::nullopt. Calling .value() on an empty optional throws std::bad_optional_access, which terminates the process with SIGABRT.

Fix

Use .value_or(DEFAULT_ERROR_STACK_TRACE_LIMIT) instead of .value(), matching the pattern used in WebKit's own ErrorConstructor.cpp and other call sites in Bun.

Repro

delete Error.stackTraceLimit;
Error.captureStackTrace({}); // SIGABRT

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[robobun]

^{Updated 12:37 PM PT - Mar 31st, 2026}

❌ @robobun, your commit 1c2c593 has 7 failures in Build #43039 (All Failures):

• test/regression/issue/26207.test.ts - code 1 on 🍎 13 x64
• test/js/bun/webview/webview.test.ts - timeout on 🍎 14 aarch64
• test/js/bun/webview/webview.test.ts - timeout on 🍎 13 aarch64
• test/js/bun/webview/webview.test.ts - timeout on 🍎 14 x64
• test/js/bun/webview/webview.test.ts - timeout on 🍎 13 x64
• test/integration/next-pages/test/dev-server.test.ts - code 1 on 🍎 13 x64
• test/cli/install/bun-run-bunfig.test.ts - code 1 on 🍎 13 x64
• test/cli/install/bun-install-lifecycle-scripts.test.ts - code 1 on 🍎 13 x64
• test/js/bun/webview/webview-chrome.test.ts - code 1 on 🍎 14 aarch64
• test/js/third_party/@azure/service-bus/azure-service-bus.test.ts - SIGILL on 🐧 13 x64-asan

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bunx bun-pr 28719

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bun-28719 --bun

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 7d31b80 and 1c2c593.

📒 Files selected for processing (2)

• src/bun.js/bindings/FormatStackTraceForJS.cpp
• test/js/node/v8/capture-stack-trace.test.js

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Walkthrough

Switches stack-trace limit retrieval to use a safe fallback (value_or(DEFAULT_ERROR_STACK_TRACE_LIMIT)) and keeps mapping explicit 0 to the default. Adds a test ensuring Error.captureStackTrace({}) does not throw when Error.stackTraceLimit is non-numeric, deleted, or undefined.

Changes

Cohort / File(s)	Summary
Stack trace handling src/bun.js/bindings/FormatStackTraceForJS.cpp	Use globalObject->stackTraceLimit().value_or(DEFAULT_ERROR_STACK_TRACE_LIMIT) instead of unconditionally calling .value(); retain normalization that maps explicit 0 to the default.
Tests test/js/node/v8/capture-stack-trace.test.js	Add test that temporarily mutates Error.stackTraceLimit (non-numeric string, deleted, undefined) and verifies Error.captureStackTrace({}) does not throw, restoring the original value in finally.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main fix: preventing crashes in Error.captureStackTrace when stackTraceLimit is nullopt, which matches the primary change in the changeset.
Description check	✅ Passed	The description covers what the PR does and includes verification through a provided repro case, but lacks explicit details on how the code was tested beyond the repro steps.

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✨ Finishing Touches

⚔️ Resolve merge conflicts

• Resolve merge conflict in branch farm/509f03ca/fix-captureStackTrace-nullopt

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