Fix reactive with new system

components/CardSlot.vue

@@ -1,6 +1,8 @@
 <script setup lang="ts">
+import type { Card } from '~/netcode/Card';
+
 export interface Props {
-    stack: string[]
+    stack: (Card | null)[]
 }
 
 const props = withDefaults(defineProps<Props>(), {
@@ -16,7 +18,7 @@ const wrapped = ref(false)
     <input type="checkbox" v-model="wrapped" />
     <div class="cards_container">
 
-        <CardPreview v-if="!wrapped" :data="props.stack.at(-1)">
+        <CardPreview v-if="!wrapped" :data="props.stack.at(-1) ?? null">
             <slot></slot>
         </CardPreview>