fix GameInner::new error handling

src/elo.rs

@@ -295,6 +295,7 @@ impl PlayerArena {
             false,
             Board::random(rand::random_range(3..=7)),
         )
+        .expect("unable to create game")
         .loop_until_result();
 
         match result {

src/game.rs

@@ -8,7 +8,8 @@ pub struct Game {
 impl Game {
     pub fn new(player1: Box<dyn Agent>, player2: Box<dyn Agent>) -> Self {
         Self {
-            inner: GameInner::new(player1, player2, true, Board::STARTING_POSITION),
+            inner: GameInner::new(player1, player2, true, Board::STARTING_POSITION)
+                .expect("unable to create game"),
         }
     }
 

src/game_inner.rs

@@ -41,26 +41,24 @@ impl GameInner {
         player2: Box<dyn Agent>,
         do_print: bool,
         board: Board,
-    ) -> Self {
+    ) -> Result<Self, &'static str> {
         let player1_color = player1.color();
         let player2_color = player2.color();
-        assert_ne!(
-            player1_color,
-            player2_color,
-            "Both players cannot have the same color {}",
-            player1_color.text()
-        );
 
-        assert_eq!(player1_color, Piece::Black, "player 1 must playing black");
+        if player1_color != Piece::Black {
-        assert_eq!(player2_color, Piece::White, "player 2 must play white");
+            return Err("player 1 must play black");
+        }
+        if player2_color != Piece::White {
+            return Err("player 2 must play white");
+        }
 
-        Self {
+        Ok(Self {
             players: [player1, player2],
             board,
             do_print,
             move_log: Vec::new(),
             first_board: board,
-        }
+        })
     }
 
     // Handle when a move is made