fix: do not over-fresh type variables

[hishamhm]

Fixes #905.

[hishamhm]

@svermeulen @mtdowling Testing of this PR with your codebases is appreciated!

[github-actions]

Teal Playground URL: https://906--teal-playground-preview.netlify.app

[mtdowling]

I'm happy to test this. Is there a way to have Luarocks install a specific branch of tl? You taught me about --dev the other day, but not sure about how to use a branch.

[catwell]

@mtdowling You can add branch = "..." in the source table of the rockspec, but for Teal it is probably easier to clone the repository, checkout the branch you want and run tl directly from there.

[hishamhm]

luarocks build --dev --branch fix-906 tl should work too!

[mtdowling]

I think I tested this and works for my project.

For future reference for my future self, I did this:

1. Cloned this repo and checked out this branch.
2. Ran luarocks build in the tl directory.
3. Verified that the tl.lua file in /opt/homebrew/share/lua/5.4/tl.lua has this change.
4. Verified that cyan installed via homebrew uses this same path.
5. Ran cyan to build my project successfully.
6. Double checked that cyan uses this file by making it error out, and it did... so my assumption was correct that it was used :)

Edit: also, hah, @hishamhm's solution is of course way better, and this change works fine.

[hishamhm]

As I half-suspected, it looks like this is not the right solution; it causes #909. Back to the drawing board.

[hishamhm]

Replacing this with #911 which looks like a more robust fix!