Bold, italic behaviour is broken on Firefox

[cocoademon]

When in "bold" mode, Firefox leaves the first character of each line non-bolded.

Repro:

• Clone the typewriter repo, run npm install and npm start.
• Open localhost:9000 in Firefox (Tested on v101.0.1 and v103.0.1)
• Add a new line
• Press Ctrl-B, and start typing. The first character will not be bold, but the remainder of the line is bold. This will occur again on new lines even without pressing Ctrl-B again.

This also happens when enabling Bold using the toolbar (on http://localhost:9000/toolbar)

Also affects Italics

It appears to work correctly in Chrome.

I'm not sure where to start debugging this behaviour, but if I had to guess I'd suggest that one avenue for investigation is the order of inputs in FF to Chrome.

[cocoademon]

In action - I pressed Ctrl-B before typing, and only pressed it once in total.

[cocoademon]

Just to clarify, there's no stylesheet affecting the first letter, the HTML for the first bold paragraph above is:

<p>H<strong>ello, this is bold</strong></p>