"Toggle between checkmarks" adds invisible stray checkmark in files in Preview mode

[claremacrae]

Steps to reproduce:

• Install and enable this plugin
• Open a file in preview mode
• Open a different file - note that it will be displayed in Preview mode, but there won't be a cursor position
• Type Ctrl/Cmd + M - i.e. run the command Hotkeys++: Toggle to-do lists

Note that the display does not change

Expected behaviour:

The file is in preview mode, so its contents should not change

Actual behaviour

The characters - [ ] are added to the start of the first line of the file

for example:

## Obsidian Hub

becomes

- [ ] ## Obsidian Hub