c2.Channel:is_twitch_channel() does not guarantee Twitch-specific functions work

[Mm2PL]

Checklist

• I'm reporting a problem with Chatterino
• I've verified that I'm running the most recent nightly build or stable release
• I've looked for my problem on the wiki
• I've searched the issues and pull requests for similar looking reports

Describe your issue

Given:

local c = c2.Channel:by_name("/whispers")
c:is_twitch_channel() -- true
c:is_mod() -- this errors: Expired or non-twitch c2.Channel used - use c2.Channel:is_valid() and c2.Channel:is_twitch_channel()

Do this after the sol migration

Screenshots

n/a

OS and Chatterino Version

commit 30560fc (HEAD -> chore/move-everything-to-sol, origin/chore/move-everything-to-sol)