Assigning theme variables to a contract causes unexpected type errors

[AndrewLeedham]

I have created a repro in the TypeScript Playground, it has a workaround for now, just thought I would mention the issue to see if it is expected.

Essentially I was expecting theme variables to be assignable to a contract with the same structure like so:

import { assignVars, createThemeContract, createTheme } from '@vanilla-extract/css';

const [theme, vars] = createTheme({
    structure: {
        value: 'blue'
    }
})

const contract = createThemeContract({
    structure: {
        value: null
    }
});

assignVars(contract, vars);