Add typecheck for passing arguments

[rin-st]

Context: #184 (comment)

Maybe for better DX we can also add args typecheck like

If (type of default argument !== type of passed argument) then throw an error "hey, wrong argument type here, see default param and example extension"

so we could be inconsistent sometimes when we need too, e.g. in this .env.example case and devs will figure it out explicitly and earlier

The rules should be set before starting to work on this