don't fire ErrServerClosed on manually interrupt signals (CTRL/CMD+C)

Former-commit-id: 673c84dd13bb99c0926aa1b4a6b4eff9745403d8

_examples/hero/overview/main.go

@@ -50,8 +50,6 @@ func main() {
 	app.Run(
 		// Start the web server at localhost:8080
 		iris.Addr("localhost:8080"),
-		// skip err server closed when CTRL/CMD+C pressed:
-		iris.WithoutServerError(iris.ErrServerClosed),
 		// enables faster json serialization and more:
 		iris.WithOptimizations,
 	)