Handle the situation where an error pops up when you change formats

[NullVoxPopuli]

Context here: https://www.reddit.com/r/javascript/comments/1lszqyf/comment/n1qilv6/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

Leading suggestion from /u/Hot-Chemistry7557

if the left panel content has been changed, then pop up a modal when user switch the choice so user can decide whether to keep the content or just discard the content and check the new demos

[johanrd]

Yeah, switching the "Change document language", should be coupled changing to a compatible demo at the same time, else the experience gets filled with errors.

I'm not even sure it needs a modal? (Or at least not if the contents haven't been edited at all). I would be fine if it was auto-replaced. Alternatively store the contents of each language in localstorage, so you can go back? – then the contents "live" in each language, and if you really want to port over between languages you can copy paste.