@MartinSchere noticed a weird error
where an unknown variable wasn't being reported
the type checker was incorrectly scoping
arguments for anonymous function definitions.
Luckily his compilation failed due to a FreeUnique
error during code gen which is good. But this may
have been the source of other mysterious FreeUnique
errors.
I also noticed that anonymous function allowed
arguments with the same name to be defined.
`fn(arg, arg)`
This now returns an error.
98c61ca151