Implemented engine return

examples/hello_world.rs

@@ -3,8 +3,8 @@ use std::sync::Arc;
 use osui::prelude::*;
 
 pub fn main() {
-    let console = Console::new();
-    console.run(app);
+    let engine = Console::new();
+    engine.run(app).expect("Failed to run engine");
 }
 
 fn app(cx: &Arc<Context>) -> View {