Fix crazyhouse illegal drop move crash

Closes #2746

lib/src/model/settings/board_preferences.dart

@@ -237,6 +237,9 @@ sealed class BoardPrefs with _$BoardPrefs implements Serializable {
       promotionMove: promotionMove,
       sideToMove: position.turn,
       validMoves: _makeLegalMoves(position, variant: variant, castlingMethod: castlingMethod),
+      droppable: variant == Variant.crazyhouse
+          ? (validDropSquares: position.legalDrops.squares.toISet())
+          : null,
       isCheck: boardHighlights && position.isCheck,
       canPromoteToKing: variant == Variant.antichess,
     );

lib/src/view/analysis/analysis_board.dart

@@ -167,7 +167,6 @@ abstract class AnalysisBoardState<
           onClearShapes: _onClearShapes,
           newShapeColor: boardPrefs.shapeColor.color,
         ),
-        enableDropMoves: analysisState.variant.hasDropMoves,
       ),
     );
   }

lib/src/widgets/game_layout.dart

@@ -172,7 +172,6 @@ class _GameLayoutState extends ConsumerState<GameLayout> {
             onClearShapes: _onClearShapes,
             newShapeColor: boardPrefs.shapeColor.color,
           ),
-          enableDropMoves: widget.boardParams.variant.hasDropMoves == true,
         );
 
         final settings = widget.boardSettingsOverrides != null

pubspec.lock

@@ -181,10 +181,10 @@ packages:
     dependency: "direct main"
     description:
       name: chessground
-      sha256: f297ef59e535f05f90ddfc1de612da7ea1b58ef84a2b7807df72cc8c43d812d4
+      sha256: e2545b2475259c5665e7c6162affa6dbcb7dd3eb3050f603162833fbb7a8a260
       url: "https://pub.dev"
     source: hosted
-    version: "8.2.1"
+    version: "9.0.0"
   cli_config:
     dependency: transitive
     description:

pubspec.yaml

@@ -14,7 +14,7 @@ dependencies:
   app_settings: ^7.0.0
   async: ^2.10.0
   auto_size_text: ^3.0.0
-  chessground: ^8.0.1
+  chessground: ^9.0.0
   clock: ^1.1.1
   collection: ^1.17.0
   connectivity_plus: ^7.0.0