getShortPinyin报错

[dreamfly32]

像 "a,b" 这种会报错，中间是英文逗号，我试了中文逗号，句号，英文句号等都可以，唯独英文逗号不行，这么什么问题？

The following RangeError was thrown while handling a gesture:
RangeError (index): Invalid value: Valid value range is empty: 0

When the exception was thrown, this was the stack:
#0 _StringBase.[] (dart:core-patch/string_patch.dart:252:55)
#1 PinyinHelper.getShortPinyin. (package:lpinyin/src/pinyin_helper.dart:51:21)

[Sky24n]

fix