fix: clean up failed pprof startup files

[buley]

Summary

BeginProfiling creates the CPU profile file before calling runtime/pprof.StartCPUProfile.
If startup fails, it panics and leaves the partially created file behind even though CPUProfiler.StartCPUProfile already cleans up that path.

Fix

Use a shared start hook for both profiling entry points, close and remove the startup file before panicking from BeginProfiling, and add a unit test that forces the failure path and verifies cleanup.

Testing

• go test ./internal/pprof

Related

• 6.0-side PR: fix: handle inspector session leak on Profiler.enable/start failure TypeScript#63290

[Copilot]

Pull request overview

Fixes a cleanup bug in the internal profiling helpers where BeginProfiling could leave behind a partially-created CPU profile file if runtime/pprof startup fails, and adds a regression test to lock the behavior in.

Changes:

• Add a package-level test seam (startCPUProfile) so tests can force StartCPUProfile failure deterministically.
• Ensure BeginProfiling closes and removes the CPU profile file before panicking when startup fails.
• Add a unit test verifying the startup-failure cleanup path.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
internal/pprof/pprof.go	Introduces a StartCPUProfile seam and uses it in both entry points; ensures failed startup removes the created CPU profile file.
internal/pprof/pprof_test.go	Adds a regression test that forces startup failure and asserts the CPU profile file is removed.

[RyanCavanaugh]

Hardening internal debug/profiling codepaths against benign failures isn't a great use of churn/risk. It's fine if a local dev has to delete this file manually after killing the process or whatever.

[buley]

Copy that - thanks for the clear answer @RyanCavanaugh