False positive when a nil slice is returned from a function

[sonalmahajan15]

Fix behavior when a nil slice is returned as in the case below.

type myIntSlice []int

func (r myIntSlice) Count() int {
	count := 0
	for _, e := range r {
		count = count + e
	}
	return count
}

func foo(input myIntSlice) myIntSlice {
	var result myIntSlice
	for _, t := range input {
		result = append(result, t)
	}
	return result
}

func test() {
	_ = foo(nil).Count()
}