fix: 修复配置页面默认配置被置空的问题

xiaomusic/static/setting.html

@@ -50,7 +50,7 @@ var vConsole = new window.VConsole();
       <input id="music_path" type="text" value="music"></input>
 
       <label for="download_path">音乐下载目录(必须是music的子目录):</label>
-      <input id="download_path" type="text"></input>
+      <input id="download_path" type="text" value='music/download'></input>
 
       <label for="conf_path">配置文件目录:</label>
       <input id="conf_path" type="text"></input>

xiaomusic/static/setting.js

@@ -78,7 +78,7 @@ $(function(){
     for (const key in data) {
       if (data.hasOwnProperty(key)) {
         const $element = $("#" + key);
-        if ($element.length) {
+        if ($element.length && data[key] !== '') {
           if (data[key] === true) {
             $element.val('true');
           } else if (data[key] === false) {