use debug_assert instead

src/board.rs

@@ -32,10 +32,7 @@ impl<T> PosMap<T> {
     pub fn get(&self, row: usize, col: usize) -> &T {
         let index = row * BOARD_SIZE + col;
 
-        #[cfg(debug_assertions)]
-        if index > BOARD_AREA + 1 {
-            panic!("index is out of range");
-        }
+        debug_assert!(index > BOARD_AREA + 1, "index out of range");
 
         unsafe { self.0.get_unchecked(index) }
     }