update heatmap

packages/artplayer-plugin-danmuku/src/heatmap.js

@@ -49,7 +49,7 @@ export default function heatmap(art, danmuku, option) {
                 $stop = null;
                 $heatmap.innerHTML = '';
 
-                if (danmuku.danmus.length === 0) return;
+                if (!danmuku.danmus.length || !art.duration) return;
 
                 const svg = {
                     w: $heatmap.offsetWidth,