fix the panic of getting out of index with response header

error.go

@@ -24,11 +24,11 @@ type ErrorResponse struct {
 func (r *ErrorResponse) Error() string {
 	RequestID := r.RequestID
 	if RequestID == "" {
-		RequestID = r.Response.Header["X-Cos-Request-Id"][0]
+		RequestID = r.Response.Header.Get("X-Cos-Request-Id")
 	}
 	TraceID := r.TraceID
 	if TraceID == "" {
-		TraceID = r.Response.Header["X-Cos-Trace-Id"][0]
+		TraceID = r.Response.Header.Get("X-Cos-Trace-Id")
 	}
 	return fmt.Sprintf("%v %v: %d %v(Message: %v, RequestId: %v, TraceId: %v)",
 		r.Response.Request.Method, r.Response.Request.URL,

error_test.go

@@ -54,3 +54,36 @@ func Test_checkResponse_no_error(t *testing.T) {
 		t.Errorf("Expected error == nil, got %+v", err)
 	}
 }
+
+func Test_checkResponse_with_error(t *testing.T) {
+	setup()
+	defer teardown()
+
+	mux.HandleFunc("/test_409", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusConflict)
+		fmt.Fprint(w, `<?xml version='1.0' encoding='utf-8' ?>
+<Error>
+	<Code>BucketAlreadyExists</Code>
+	<Message>The requested bucket name is not available.</Message>
+	<Resource>testdelete-1253846586.cos.ap-guangzhou.myqcloud.com</Resource>
+	<RequestId>NTk0NTRjZjZfNTViMjM1XzlkMV9hZTZh</RequestId>
+	<TraceId>OGVmYzZiMmQzYjA2OWNhODk0NTRkMTBiOWVmMDAxODc0OWRkZjk0ZDM1NmI1M2E2MTRlY2MzZDhmNmI5MWI1OTBjYzE2MjAxN2M1MzJiOTdkZjMxMDVlYTZjN2FiMmI0NTk3NWFiNjAyMzdlM2RlMmVmOGNiNWIxYjYwNDFhYmQ=</TraceId>
+</Error>`)
+	})
+
+	req, _ := http.NewRequest("GET", client.BaseURL.ServiceURL.String()+"/test_409", nil)
+	resp, _ := client.client.Do(req)
+	err := checkResponse(resp)
+
+	if e, ok := err.(*ErrorResponse); ok {
+		if e.Error() == "" {
+			t.Errorf("Expected e.Error() not empty, got %+v", e.Error())
+		}
+		if e.Code != "BucketAlreadyExists" {
+			t.Errorf("Expected BucketAlreadyExists error, got %+v", e.Code)
+		}
+	} else {
+		t.Errorf("Expected ErrorResponse error, got %+v", err)
+	}
+
+}