fix: suppress http.ErrAbortHandler in recover

[MondayCha]

This PR resolves an issue where http.ErrAbortHandler panics are incorrectly logged as errors by the gin.Recovery middleware.

The current gin.Recovery middleware only handles "broken pipe" errors, causing it to log unnecessary stack traces when a client prematurely closes a connection. This behavior is misleading, as http.ErrAbortHandler is intentionally used by httputil.ReverseProxy to abort requests and is not a true application error.

This change modifies the Recovery middleware to explicitly check for http.ErrAbortHandler and suppress the logging of stack traces for this specific panic. This aligns the middleware with the intended behavior of the Go standard library and improves log clarity by filtering out expected panics.

Related Issue

• Reverse Proxy issues #1714

References

• net/http/httputil: Question about new panic in ReverseProxy golang/go#28239: The Go issue discussing the intended use of http.ErrAbortHandler.
• middleware: suppress http.ErrAbortHandler in recoverer go-chi/chi#449: A similar implementation in the go-chi/chi library.

Similar PRs

• treat http.ErrAbortHandler as broken pipe too #2590 (lacks tests)
• Treat http.ErrAbortHandler as broken pipe #3487 (lacks tests)