Fix a bit of syntax

[L0neGamer]

Note that this requires

source-repository-package
    type: git
    location: https://github.com/L0neGamer/typerep-map.git
    tag: 43026d99e1b63d049e8e79641c2e7972a5611629

to test as typerep has old deps, and you can't even use aeson 2.2+

Fixes #73

[Miezhiko]

I can approve it fixes error

[simmsb]

Thanks!