Bug: Broken Markdown Link + Linkification

### Steps:
1. New Note
2. Enable Markdown
3. Type `[Hello`
4. Switch to other document and back to the newly created note

As a result `[Hello` will be linkified.

Thank you @aerych for spotting this one!!

Reproduce the issue in the macOS app by creating a note, enabling Markdown, entering `[Hello`, and switching documents. Trace the Markdown linkification path involved when returning to the note; done when the incomplete `[Hello` text remains unlinked.

Written by the indexing model from the issue text.