Ensure MultiError returned when both Before and After funcs given

context_test.go

@@ -154,9 +154,10 @@ func TestContext_GlobalFlag(t *testing.T) {
 	app.Flags = []Flag{
 		StringFlag{Name: "global, g", Usage: "global"},
 	}
-	app.Action = func(c *Context) {
+	app.Action = func(c *Context) error {
 		globalFlag = c.GlobalString("global")
 		globalFlagSet = c.GlobalIsSet("global")
+		return nil
 	}
 	app.Run([]string{"command", "-g", "foo"})
 	expect(t, globalFlag, "foo")