Fix Underflow bug, and require game path in arg

src/main.rs

@@ -19,7 +19,8 @@ fn main() {
     let window = init_window(&event_loop);
     let mut pixels = init_pixels(&window);
 
-    let rom_path = Path::new("./games/c8games/INVADERS");
+    let path = std::env::args().nth(1).expect("No Path Provided!");
+    let rom_path = Path::new(&path);
     chip8.load_rom(rom_path).expect("Unable to load ROM");
 
     TimerManager::start();

src/periph.rs

@@ -137,14 +137,14 @@ impl Timer {
 
     pub fn tick(&mut self) {
         if self.enabled {
-            self.remaining -= 1;
-
             if self.remaining == 0 {
                 self.enabled = false;
 
                 if self.beep_enabled {
                     Self::beep();
                 }
+            } else {
+                self.remaining -= 1;
             }
         }
     }