FR: "Function not found" error should spec desired arity, and perhaps available arities

[barries]

Right now, it's hard to tell which overload is missing when calling with a dynamic number of args. Adding the requested arity, and perhaps the available arities, would make this error much more easily diagnosable.

Thanks!

[schungx]

Agree. However, this will be a breaking change, so would need to wait for the next major version.