修复: byte/rune 长度混淆及错误位置丢失

engine.go

@@ -1,6 +1,7 @@
 package utpl
 
 import (
+	"errors"
 	"fmt"
 
 	"gitea.1216.top/lxy/u-tpl/internal"
@@ -114,8 +115,16 @@ func wrapParseError(err error, name string) error {
 	if _, ok := err.(*ParseError); ok {
 		return err
 	}
+	msg := fmt.Sprintf("template %q: %s", name, err.Error())
+	var posErr *internal.PosError
+	if errors.As(err, &posErr) {
+		return &ParseError{
+			Pos:     Position{Line: posErr.Line, Column: posErr.Col},
+			Message: msg,
+		}
+	}
 	return &ParseError{
-		Pos:     Position{Line: 0, Column: 0},
-		Message: fmt.Sprintf("template %q: %s", name, err.Error()),
+		Pos:     Position{},
+		Message: msg,
 	}
 }