fix: await nextTick before setting video src on first preview

editor/components/PreviewPanel.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref, watch, computed } from 'vue'
+import { ref, watch, computed, nextTick } from 'vue'
 
 const props = defineProps<{
   videoUrl: string | null
@@ -9,7 +9,8 @@ const videoRef = ref<HTMLVideoElement | null>(null)
 const playing = ref(false)
 const paused = ref(false)
 
-watch(() => props.videoUrl, (url) => {
+watch(() => props.videoUrl, async (url) => {
+  await nextTick()
   if (!videoRef.value || !url) return
   videoRef.value.src = url
   playing.value = false