Improve exception message raised in GamePlayers.__getitem__ (#702)

Author: rahulsavani

src/pygambit/game.pxi

@@ -307,7 +307,10 @@ class GamePlayers:
                 raise ValueError(f"Game has multiple players with label '{index}'")
             return matches[0]
         if isinstance(index, int):
-            return Player.wrap(self.game.deref().GetPlayer(index + 1))
+            try:
+                return Player.wrap(self.game.deref().GetPlayer(index + 1))
+            except IndexError:
+                raise IndexError("Index out of range") from None
         raise TypeError(f"Player index must be int or str, not {index.__class__.__name__}")
 
     @property

tests/test_players.py

@@ -40,11 +40,12 @@ def test_player_index_by_string():
 def test_player_index_out_of_range():
     game = gbt.Game.new_table([2, 2])
     assert len(game.players) == 2
-    with pytest.raises(IndexError):
+    exp_error_msg = "Index out of range"
+    with pytest.raises(IndexError, match=exp_error_msg):
         _ = game.players[2]
-    with pytest.raises(IndexError):
+    with pytest.raises(IndexError, match=exp_error_msg):
         _ = game.players[3]
-    with pytest.raises(IndexError):
+    with pytest.raises(IndexError, match=exp_error_msg):
         _ = game.players[-1]