优化 ParseByLayout 方法

parser.go

@@ -59,15 +59,16 @@ func ParseByFormat(value, format string, timezone ...string) Carbon {
 // ParseByLayout parses a time string as a Carbon instance by layout.
 // 通过布局模板将时间字符串解析成 Carbon 实例
 func (c Carbon) ParseByLayout(value, layout string, timezone ...string) Carbon {
+	if len(value) == 0 {
+		c.Error = invalidValueError(value)
+		return c
+	}
 	if len(timezone) > 0 {
 		c.loc, c.Error = getLocationByTimezone(timezone[0])
 	}
 	if c.Error != nil {
 		return c
 	}
-	if len(value) == 0 {
-		return c
-	}
 	if len(layout) == 0 {
 		layout = defaultLayout
 	}

parser_unit_test.go

@@ -240,7 +240,7 @@ func TestCarbon_Issue232(t *testing.T) {
 		{
 			name:   "case1",
 			carbon: Parse("0000-01-01 00:00:00"),
-			want:   "0000-01-01 00:00:00",
+			want:   "",
 		},
 		{
 			name:   "case2",