add package tests

src/main.rs

@@ -21,6 +21,6 @@ fn main() -> eframe::Result<()> {
     eframe::run_native(
         "(Yet-to-be-named) Graphing Software",
         eframe::NativeOptions::default(),
-        Box::new(|cc| Box::new(math_app::MathApp::new(cc))),
+        Box::new(|cc| Ok(Box::new(math_app::MathApp::new(cc)))),
     )
 }