This test exercises stub methods functionality with variadic parameters.

In golang/go#61693 stubmethods was panicking in this case.

-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

type C int

func F(err ...error) {}

func _() {
	var x error
	F(x, C(0)) //@quickfix(re"C.0.", re"missing method Error", stub)
}
-- @stub/main.go --
@@ -5 +5,5 @@
+// Error implements error.
+func (c C) Error() string {
+	panic("unimplemented")
+}
+