Refactor StringsToInt64s (#29967)

And close #27176

modules/base/tool.go

@@ -150,13 +150,16 @@ func TruncateString(str string, limit int) string {
 
 // StringsToInt64s converts a slice of string to a slice of int64.
 func StringsToInt64s(strs []string) ([]int64, error) {
-	ints := make([]int64, len(strs))
-	for i := range strs {
-		n, err := strconv.ParseInt(strs[i], 10, 64)
+	if strs == nil {
+		return nil, nil
+	}
+	ints := make([]int64, 0, len(strs))
+	for _, s := range strs {
+		n, err := strconv.ParseInt(s, 10, 64)
 		if err != nil {
-			return ints, err
+			return nil, err
 		}
-		ints[i] = n
+		ints = append(ints, n)
 	}
 	return ints, nil
 }