diff --git a/src/samples/tic-tac-toe.ts b/src/samples/tic-tac-toe.ts
index 7526af9..ee4fab7 100644
--- a/src/samples/tic-tac-toe.ts
+++ b/src/samples/tic-tac-toe.ts
@@ -59,25 +59,23 @@ async function setup(game: TicTacToeGame) {
 registry.register('setup', setup);
 
 async function turn(game: TicTacToeGame, turnPlayer: PlayerType, turnNumber: number) {
-    const playCmd = await game.prompt(
+    const {player, row, col} = await game.prompt(
         'play <player> <row:number> <col:number>',
         (command) => {
             const [player, row, col] = command.params as [PlayerType, number, number];
 
             if (player !== turnPlayer) {
-                return `Invalid player: ${player}. Expected ${turnPlayer}.`;
+                throw new Error(`Invalid player: ${player}. Expected ${turnPlayer}.`);
+            } else if (!isValidMove(row, col)) {
+                throw new Error(`Invalid position: (${row}, ${col}). Must be between 0 and ${BOARD_SIZE - 1}.`);
+            } else if (isCellOccupied(game, row, col)) {
+                throw new Error(`Cell (${row}, ${col}) is already occupied.`);
+            } else {
+                return { player, row, col };
             }
-            if (!isValidMove(row, col)) {
-                return `Invalid position: (${row}, ${col}). Must be between 0 and ${BOARD_SIZE - 1}.`;
-            }
-            if (isCellOccupied(game, row, col)) {
-                return `Cell (${row}, ${col}) is already occupied.`;
-            }
-            return null;
         },
         game.value.currentPlayer
     );
-    const [player, row, col] = playCmd.params as [PlayerType, number, number];
 
     placePiece(game, row, col, turnPlayer);