Cursor jumps around while deleting emoji

[miciasto]

• Searched existing issues to avoid creating duplicates.
• Confirmed that it can be reproduced in built-in themes without customized css.
• Searched http://support.typora.io/

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Describe the bug
Cursor jumps around while deleting emoji.

To Reproduce

1. Enter the following text on a new line:

:smile:

2. Move the cursor to the start of the line
3. Press the delete key 3 times

Observed:

sile:

Expected:

ile:

Desktop: OS: Windows 11 64 bit
Typora Version: 1.8.3-dev

[miciasto]

May be a related issue?

To Reproduce

1. Enter the following text on a new line:

==:smile:==

2. Using the arrow keys (not the mouse), move the cursor to imcmediately before the first : character
3. Press the delete key 7 times

Observed:

==:smile:==

that is, nothing happened, it is as if the delete key does not work.

Expected:

====

[abnerlee]

should be fixed in 1.8.6

[miciasto]

Tested on 1.8.8 and confirmed issue is 99% resolved. One press of the delete key is ignored but it works if you hit it again.

Thank you