fix(handler): opsCaptureWriter 释放后访问 nil panic

Fixes #3961

backend/internal/handler/ops_capture_writer_nil_test.go

@@ -0,0 +1,36 @@
+package handler
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestOpsCaptureWriter_NilInnerWriter_NoPanic(t *testing.T) {
+	w := &opsCaptureWriter{}
+	w.ResponseWriter = nil
+
+	assert.NotPanics(t, func() {
+		assert.Equal(t, 0, w.Status())
+	}, "Status() on released writer must not panic")
+
+	assert.NotPanics(t, func() {
+		assert.Equal(t, -1, w.Size())
+	}, "Size() on released writer must not panic")
+
+	assert.NotPanics(t, func() {
+		assert.False(t, w.Written())
+	}, "Written() on released writer must not panic")
+
+	assert.NotPanics(t, func() {
+		n, err := w.Write([]byte("test"))
+		assert.Equal(t, 0, n)
+		assert.NoError(t, err)
+	}, "Write() on released writer must not panic")
+
+	assert.NotPanics(t, func() {
+		n, err := w.WriteString("test")
+		assert.Equal(t, 0, n)
+		assert.NoError(t, err)
+	}, "WriteString() on released writer must not panic")
+}

backend/internal/handler/ops_error_logger.go

@@ -498,7 +498,31 @@ func releaseOpsCaptureWriter(w *opsCaptureWriter) {
 	opsCaptureWriterPool.Put(w)
 }
 
+func (w *opsCaptureWriter) Status() int {
+	if w.ResponseWriter == nil {
+		return 0
+	}
+	return w.ResponseWriter.Status()
+}
+
+func (w *opsCaptureWriter) Size() int {
+	if w.ResponseWriter == nil {
+		return -1
+	}
+	return w.ResponseWriter.Size()
+}
+
+func (w *opsCaptureWriter) Written() bool {
+	if w.ResponseWriter == nil {
+		return false
+	}
+	return w.ResponseWriter.Written()
+}
+
 func (w *opsCaptureWriter) Write(b []byte) (int, error) {
+	if w.ResponseWriter == nil {
+		return 0, nil
+	}
 	if w.Status() >= 400 && w.limit > 0 && w.buf.Len() < w.limit {
 		remaining := w.limit - w.buf.Len()
 		if len(b) > remaining {
@@ -511,6 +535,9 @@ func (w *opsCaptureWriter) Write(b []byte) (int, error) {
 }
 
 func (w *opsCaptureWriter) WriteString(s string) (int, error) {
+	if w.ResponseWriter == nil {
+		return 0, nil
+	}
 	if w.Status() >= 400 && w.limit > 0 && w.buf.Len() < w.limit {
 		remaining := w.limit - w.buf.Len()
 		if len(s) > remaining {