From 7822a4c1cb2862e8883e68b7ea5bc61d00c3024a Mon Sep 17 00:00:00 2001
From: Kevin Wan <wanjunfeng@gmail.com>
Date: Sat, 13 Jan 2024 22:11:19 +0800
Subject: [PATCH] chore: refactor mapping errors (#3843)

---
 core/mapping/unmarshaler.go      | 3 ++-
 core/mapping/unmarshaler_test.go | 2 +-
 core/mapping/utils.go            | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/core/mapping/unmarshaler.go b/core/mapping/unmarshaler.go
index b06385b4..277edc5e 100644
--- a/core/mapping/unmarshaler.go
+++ b/core/mapping/unmarshaler.go
@@ -250,8 +250,9 @@ func (u *Unmarshaler) fillSliceFromString(fieldType reflect.Type, value reflect.
 func (u *Unmarshaler) fillSliceValue(slice reflect.Value, index int,
 	baseKind reflect.Kind, value any, fullName string) error {
 	if value == nil {
-		return errUnsupportedType
+		return errNilSliceElement
 	}
+
 	ithVal := slice.Index(index)
 	switch v := value.(type) {
 	case fmt.Stringer:
diff --git a/core/mapping/unmarshaler_test.go b/core/mapping/unmarshaler_test.go
index 18104537..d783670b 100644
--- a/core/mapping/unmarshaler_test.go
+++ b/core/mapping/unmarshaler_test.go
@@ -1340,7 +1340,7 @@ func TestUnmarshalNullableSlice(t *testing.T) {
 	}
 
 	ast := assert.New(t)
-	ast.Equal(UnmarshalKey(m, &v), errUnsupportedType)
+	ast.Equal(UnmarshalKey(m, &v), errNilSliceElement)
 }
 
 func TestUnmarshalIntSlice(t *testing.T) {
diff --git a/core/mapping/utils.go b/core/mapping/utils.go
index 67ea0ae3..d7c84af4 100644
--- a/core/mapping/utils.go
+++ b/core/mapping/utils.go
@@ -36,6 +36,7 @@ const (
 var (
 	errUnsupportedType  = errors.New("unsupported type on setting field value")
 	errNumberRange      = errors.New("wrong number range setting")
+	errNilSliceElement  = errors.New("null element for slice")
 	optionsCache        = make(map[string]optionsCacheValue)
 	cacheLock           sync.RWMutex
 	structRequiredCache = make(map[reflect.Type]requiredCacheValue)