Improve usages of json.Unmarshal

option/json.go

@@ -1,8 +1,6 @@
 package option
 
 import (
-	"bytes"
-
 	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/json"
@@ -69,7 +67,5 @@ func UnmarshallExcluded(inputContent []byte, parentObject any, object any) error
 	if err != nil {
 		return err
 	}
-	decoder := json.NewDecoder(bytes.NewReader(inputContent))
-	decoder.DisallowUnknownFields()
-	return decoder.Decode(object)
+	return json.UnmarshalDisallowUnknownFields(inputContent, object)
 }