From ee6b852959ce70807705f3891391b33a245ab494 Mon Sep 17 00:00:00 2001
From: Spiegel <spiegel.im.spiegel@gmail.com>
Date: Sat, 9 May 2026 11:20:37 +0900
Subject: [PATCH] fix: guard nil Err and propagate zap context encode errors

---
 errs.go                     |  8 +++++++-
 errs_test.go                | 20 ++++++++++++++++++++
 zapobject/zapobject.go      |  4 +++-
 zapobject/zapobject_test.go | 26 ++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 zapobject/zapobject_test.go

diff --git a/errs.go b/errs.go
index 7d15b1d..0600e2f 100644
--- a/errs.go
+++ b/errs.go
@@ -141,12 +141,18 @@ func (e *Error) Error() string {
 	if e == nil {
 		return nilAngleString
 	}
-	errMsg := e.Err.Error()
+	var errMsg string
+	if e.Err != nil {
+		errMsg = e.Err.Error()
+	}
 	var causeMsg string
 	if e.Cause != nil {
 		causeMsg = e.Cause.Error()
 	}
 	if len(causeMsg) == 0 {
+		if len(errMsg) == 0 {
+			return nilAngleString
+		}
 		return errMsg
 	}
 	if len(errMsg) == 0 {
diff --git a/errs_test.go b/errs_test.go
index 1daa8b6..2ea39c7 100644
--- a/errs_test.go
+++ b/errs_test.go
@@ -447,6 +447,26 @@ func TestUnwraps(t *testing.T) {
 	}
 }
 
+func TestErrorWithNilErr(t *testing.T) {
+	testCases := []struct {
+		name string
+		err  *Error
+		want string
+	}{
+		{name: "empty", err: &Error{}, want: "<nil>"},
+		{name: "cause only", err: &Error{Cause: os.ErrInvalid}, want: "invalid argument"},
+		{name: "err and cause", err: &Error{Err: os.ErrNotExist, Cause: os.ErrInvalid}, want: "file does not exist: invalid argument"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := tc.err.Error(); got != tc.want {
+				t.Errorf("Error() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
 /* Copyright 2019-2023 Spiegel
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/zapobject/zapobject.go b/zapobject/zapobject.go
index 184cb4d..1427063 100644
--- a/zapobject/zapobject.go
+++ b/zapobject/zapobject.go
@@ -45,7 +45,9 @@ func (e ErrObject) MarshalLogObject(enc zapcore.ObjectEncoder) error {
 			sort.Strings(keys)
 			enc.OpenNamespace("context")
 			for _, k := range keys {
-				_ = enc.AddReflected(k, ee.Context[k])
+				if err := enc.AddReflected(k, ee.Context[k]); err != nil {
+					return err
+				}
 			}
 		}
 	} else {
diff --git a/zapobject/zapobject_test.go b/zapobject/zapobject_test.go
new file mode 100644
index 0000000..9913c38
--- /dev/null
+++ b/zapobject/zapobject_test.go
@@ -0,0 +1,26 @@
+package zapobject
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/goark/errs"
+	"go.uber.org/zap/zapcore"
+)
+
+type addReflectedErrEncoder struct {
+	*zapcore.MapObjectEncoder
+}
+
+func (e *addReflectedErrEncoder) AddReflected(_ string, _ interface{}) error {
+	return errors.New("add reflected failed")
+}
+
+func TestMarshalLogObject_AddReflectedError(t *testing.T) {
+	err := errs.New("wrapped", errs.WithContext("bad", func() {}))
+	enc := &addReflectedErrEncoder{MapObjectEncoder: zapcore.NewMapObjectEncoder()}
+
+	if got := New(err).MarshalLogObject(enc); got == nil {
+		t.Fatal("MarshalLogObject() = nil, want non-nil error")
+	}
+}