fix: only validate psu path if its not empty

src/screens/Loading.svelte

@@ -133,10 +133,11 @@
 
     if (!$firstStartup) {
       currentLoadingInfo.set('Checking osu installation path...');
+      if ($osuInstallationPath && $osuInstallationPath.length > 0) {
         const validFolder = await isValidOsuFolder($osuInstallationPath);
         if (!validFolder) {
-        osuInstallationPath.set('');
           await config.value<string>('osu_installation_path').set('');
+          osuInstallationPath.set('');
           sileo.error({
             title: 'Hmm...',
             description: 'Your previously set osu! installation path seems to be invalid.',
@@ -165,6 +166,7 @@
           currentSkin.set(skin);
         }
       }
+    }
 
     currentLoadingInfo.set('Checking for EZPPLauncher updates...');
     const launcherUpdate = await git.hasUpdate($launcherVersion);