From f1ba7b3153bd555cb213ba17a1d31168bf8584b7 Mon Sep 17 00:00:00 2001
From: John Wang <johncwang@gmail.com>
Date: Fri, 22 Nov 2024 19:59:15 -0800
Subject: [PATCH] fix: `type/stringsutil`: fix `ToUpperFirst()` for zero length
 input

---
 type/stringsutil/stringsutil.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/type/stringsutil/stringsutil.go b/type/stringsutil/stringsutil.go
index 91d60990..ec64a32b 100644
--- a/type/stringsutil/stringsutil.go
+++ b/type/stringsutil/stringsutil.go
@@ -82,7 +82,9 @@ func ToUpperFirst(s1 string, lowerRest bool) string {
 		s1 = strings.ToLower(s1)
 	}
 	a1 := []rune(s1)
-	a1[0] = unicode.ToUpper(a1[0])
+	if len(a1) > 0 {
+		a1[0] = unicode.ToUpper(a1[0])
+	}
 	return string(a1)
 }