🐛 bug: Handle panics in client execFunc without crashing callers

[Copilot]

Description

client.execFunc() launched request execution in a goroutine without panic recovery. A panic from the transport path could terminate the process and leave the caller blocked waiting on pooled channels.

Changes introduced

• Panic containment in execFunc

  • Add a recover() path around the goroutine body in client/core.go.
  • Convert panics into client panic: ... errors sent through errChan so callers fail normally instead of crashing.

• Pool/resource safety

  • Release any partially acquired Response before reporting the panic.
  • Preserve the existing channel-drain / timeout behavior so pooled channels are not left in a bad state.

• Regression coverage

  • Add a focused client test using a panicking transport to verify execFunc() returns an error and no response.

defer func() {
	if r := recover(); r != nil {
		if resp != nil {
			ReleaseResponse(resp)
		}
		errChan <- fmt.Errorf("client panic: %v", r)
	}
}()

• Benchmarks: No benchmark impact; change is on an exceptional panic path.
• Documentation Update: No docs changes required.
• Changelog/What's New: Not added.
• Migration Guide: Not needed; behavior changes only for panic cases.
• API Alignment with Express: Not applicable.
• API Longevity: Keeps existing client API intact; panics are surfaced as regular errors.
• Examples: Added a regression test covering a panicking transport.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• Enhancement (improvement to existing features and functionality)
• Documentation update (changes to documentation)
• Performance improvement (non-breaking change which improves efficiency)
• Code consistency (non-breaking change which improves code reliability and robustness)

Checklist

Before you submit your pull request, please make sure you meet these requirements:

• Followed the inspiration of the Express.js framework for new functionalities, making them similar in usage.
• Conducted a self-review of the code and provided comments for complex or critical parts.
• Updated the documentation in the /docs/ directory for Fiber's documentation.
• Added or updated unit tests to validate the effectiveness of the changes or new features.
• Ensured that new and existing unit tests pass locally with the changes.
• Verified that any new dependencies are essential and have been agreed upon by the maintainers/community.
• Aimed for optimal performance with minimal allocations in the new code.
• Provided benchmarks for the new code to analyze and improve upon.

Commit formatting

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[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.33%. Comparing base (e5e93e6) to head (bedaffc).

Files with missing lines	Patch %	Lines
client/core.go	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4365      +/-   ##
==========================================
- Coverage   91.39%   91.33%   -0.06%     
==========================================
  Files         132      132              
  Lines       13098    13104       +6     
==========================================
- Hits        11971    11969       -2     
- Misses        710      716       +6     
- Partials      417      419       +2     

Flag	Coverage Δ
unittests	91.33% <71.42%> (-0.06%)	⬇️

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[Copilot]

Pull request overview

This PR improves the Fiber client execution path by containing panics raised during asynchronous request execution and returning them as normal client errors instead of allowing goroutine panics to crash the process.

Changes:

• Adds panic recovery in client.execFunc() and reports recovered panics through the existing error channel.
• Releases any partially acquired client Response during panic recovery.
• Adds regression coverage with a panicking transport implementation.

Reviewed changes

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

File	Description
client/core.go	Adds panic recovery and panic-to-error conversion inside the request execution goroutine.
client/core_test.go	Adds a test transport that panics and verifies execFunc() returns an error with no response.