Make sure we don't double-buffer an input causing undo to become stuck

src/systems/keyboardInput.js

@@ -11,6 +11,7 @@ game.system.KeyboardInput = (undoSystem) => {
       const entity = entities[id];
       if (entity.hasComponent('controllable')) {
         const controls = entity.components.controllable.controls;
+        if (!changedIds.has(entity.id)) {
           if (controls.includes('left') && keys['ArrowLeft']) {
             entity.addComponent(game.components.Momentum({ dx: -1, dy: 0 }));
           } else if (controls.includes('right') && keys['ArrowRight']) {
@@ -22,6 +23,7 @@ game.system.KeyboardInput = (undoSystem) => {
           }
         }
       }
+    }
     if (keys['z']) {
       undoSystem.undo(entities);
     }