caddyhttp: drop defensive checks in UnwrapResponseWriterAs

Per review, the nil-pointer guard and the next == w self-reference
guard defended against shapes that no in-tree ResponseWriter wrapper
produces. Drop both, simplifying the loop. Also remove the
self-reference test that exercised the now-removed guard.

modules/caddyhttp/responsewriter.go

@@ -68,7 +68,7 @@ func (rww *ResponseWriterWrapper) Unwrap() http.ResponseWriter {
 // own type assertions and cannot see past a wrapper.
 func UnwrapResponseWriterAs[T any](w http.ResponseWriter) (T, bool) {
 	var zero T
-	for w != nil {
+	for {
 		if t, ok := any(w).(T); ok {
 			return t, true
 		}
@@ -76,13 +76,8 @@ func UnwrapResponseWriterAs[T any](w http.ResponseWriter) (T, bool) {
 		if !ok {
 			return zero, false
 		}
-		next := u.Unwrap()
-		if next == w {
-			return zero, false
-		}
-		w = next
+		w = u.Unwrap()
 	}
-	return zero, false
 }
 
 // ErrNotImplemented is returned when an underlying

modules/caddyhttp/responsewriter_test.go

@@ -6,7 +6,6 @@ import (
 	"net/http"
 	"strings"
 	"testing"
-	"time"
 )
 
 type responseWriterSpy interface {
@@ -243,21 +242,3 @@ func TestUnwrapResponseWriterAs_NotFound(t *testing.T) {
 	}
 }
 
-type selfUnwrapWriter struct{ baseRespWriter }
-
-func (s *selfUnwrapWriter) Unwrap() http.ResponseWriter { return s }
-
-func TestUnwrapResponseWriterAs_StopsOnSelfReference(t *testing.T) {
-	// Defensive: a wrapper whose Unwrap returns itself must not loop forever.
-	loop := &selfUnwrapWriter{}
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		_, _ = UnwrapResponseWriterAs[targetIface](loop)
-	}()
-	select {
-	case <-done:
-	case <-time.After(time.Second):
-		t.Fatal("UnwrapResponseWriterAs hung on self-referential Unwrap")
-	}
-}