Ask to save changes when no changes are made

[KevinSource0]

Steps to reproduce:

1. Open a markdown file with Milkdown
2. After the file is opened, immediately click on close without making any changes.

Expected:
File closed successfully without any pop-up.

Actual:
Prompted with: Do you want to save the changes you made to xxxx.md?

Milkdown version: 0.0.15

[sgon00]

I just knew this extension and checking the issues first before using it. This issue is kinda showstopper to me.
I don't want the editor do any changes automatically without my permission.
The editor should NOT auto modify my file.
All the edits should be done manually by me only.

Btw, a good extension and thank the author very much for developing it.

PS: I will only start using it when the extension stop editing my file automatically.

[alexhs1]

please fix this as its very annoying being prompted with save or dont save prompt everytime I open a md file and then try and close it. Otherwise this extension is perfect