I asked a question at the ReScript forum. The answers suggested that there could be a bug in the extension, hence this issue.

I have created a repo containing the example here. Please have a look in FormTest.res to see the type inference I'm wondering about.

Can you confirm that it's a bug, or is it because I'm missing to open the other module or something else?

Recreating the example in the ReScript playground shows that the type is inferred.

Thanks for considering this.