[Bug] WSYWIG formatting with key shortcuts results in malformed markdown on export

[Carefully-bound]

Initial checklist

• [X] I agree to follow the code of conduct
• [X] I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected packages and versions

core - 7.4.0

Link to runnable example

No response

Steps to reproduce

Reproduced both on Milkdown Playground and on a SvelteKit local app.

1. Navigate to https://milkdown.dev/playground
2. In the left panel, type anything.
3. Press control + i
4. Type test (be sure to end with a space)
5. Press control + i again
6. Type anything else.

Resulting text in the right panel will not be valid markdown, such as:

Expected behavior

For the example

normal italic text

Text should not have spaces between the markdown signal characters and the word, e.g., normal *italic* text

Actual behavior

For the example

normal italic text

Text has a trailing space before the markdown close character, e.g., normal *italic *text

Runtime

Chrome

OS

macOS

Build and bundle tools

Other (please specify in steps to reproduce)