When spelling [bold, italic, underline, strike ] Chinese, deleting spelling letters causes the editor to lose focus

[Thassurian]

当我正在拼写一个中文词语的时候，如果恰好是在 加粗/倾斜/下划线/删除线 字体样式下的第一个字，然后我删除正在拼写的字母，编辑器就会失去焦点并且取消选中字体样式。 When I am spelling a Chinese word, if it happens to be the first word in bold/italic/underline/strike font styles, and then I delete the spelling letter, the editor will lose focus and deselect the font style..

Steps for Reproduction

1. 选中[bold, italic, underline, strike ]中的任意一个字体样式， Select any font style in [bold, italic, underline, strike ],
2. 输入一个拼写字母。 Enter a spelling letter.
3. 删除这个字母。 Delete this letter.

可以在非安卓手机浏览器外的任意浏览器复现。 It can be reproduced in any browser other than Android mobile phone browser。

Version:

quill.js 1.3.7