In inline code double hypen does not work, weird behavior afterwards

[Adspectus]

In a text block when rendering some part as inline code, a double hyphen like --option does not work. Both hyphens will be rendered as a dash. Moreover if you will work around this, afterwards any keystroke leads to erasing the character in front of the cursor and replacing it with a dash

Add a text block with some text, then mark something as code and start typing two hyphens after each other. See attached screen cast.

Expected is that in inline code, 2 hyphens are not getting rendered as dash since 2 hyphens are valid in code.

Screen cast attached.

Kirby 3.4.2

• OS: Ubuntu 18.04
• Browser: Firefox 79.0

[afbora]

Duplicated with #184