Panics for functions without body closures

[fatih]

This panics:

package main

func foo(bar string)

func main() {}

This is valid AST, but not valid go program. Can easily happen during refactor or if we write new code.

[ghost]

A function declaration without a body is valid Go. Such a declaration provides the signature for a function implemented outside Go, such as an assembly routine.

[fatih]

Oh, that's indeed totally true! Thanks for the reminder @claudia-jones. In any case, we need to fix this.