DevTools: guard against undefined component stack in Profiler SidebarEventInfo

[everettbu]

Mirror of facebook/react#35054
Original author: Abhra0404

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Fixes a crash in the DevTools Profiler where calling .map on an undefined component stack could throw: "Cannot read properties of undefined (reading 'map')". See issue react/react#35049.

What I changed:

• Ensure stackToComponentLocations(componentStack) is treated as an array before calling .map in packages/react-devtools-shared/src/devtools/views/Profiler/SidebarEventInfo.js.
• Removed inline Flow type annotations in SidebarEventInfo.js to keep the file valid JavaScript in this build.

Why:

• When componentStack was undefined (e.g. during navigation in React Native), the code attempted to call .map on the result, causing the Profiler to crash. Guarding the .map call prevents the crash.

Notes / Testing:

• The fix was committed to branch fix/profiler-crash-35049 in my fork (Abhra0404/react).
• Please review the removal of Flow annotations; if you prefer Flow types retained, I can reintroduce them in a Flow-compatible way.

This PR references and aims to address react/react#35049.

[greptile-apps]

Greptile Overview

Greptile Summary

This PR fixes a crash in the DevTools Profiler that occurred when componentStack was undefined during navigation in React Native. The fix adds a defensive guard (|| []) to ensure .map is always called on an array, preventing the "Cannot read properties of undefined (reading 'map')" error.

Key changes:

• Added null-safety guard: (stackToComponentLocations(componentStack) || []) on line 81
• Removed Flow type annotations (FunctionLocationProps, SchedulingEventProps) to maintain JavaScript compatibility
• Removed return type annotation from SidebarEventInfo function

Note: The defensive || [] guard is technically redundant based on the stackToComponentLocations implementation (which always returns an array), but provides additional safety against unexpected edge cases or future changes.

Confidence Score: 4/5

• This PR is safe to merge with minimal risk - addresses a specific crash with defensive programming
• The fix is defensive and won't introduce new issues. The || [] guard ensures robustness even though stackToComponentLocations theoretically always returns an array. Removing Flow annotations is acceptable for JS files. Score of 4 (not 5) because the root cause analysis isn't fully clear - the defensive fix works around a symptom that theoretically shouldn't occur based on the stackToComponentLocations implementation.
• No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
packages/react-devtools-shared/src/devtools/views/Profiler/SidebarEventInfo.js	4/5	Adds defensive null-safety guard for stackToComponentLocations call and removes Flow type annotations for JS compatibility

[greptile-apps]

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[github-actions]

Closing this pull request after a prolonged period of inactivity. If this issue is still present in the latest release, please ask for this pull request to be reopened. Thank you!