throw error on startup failure

src/index.js

@@ -39,6 +39,7 @@ async function setStagingPath() {
     }
     else {
         showServerError("setStagingPath", response.status, text);
+        throw new Error("Can not get staging path");
     }
 }
 
@@ -55,6 +56,8 @@ async function setFileList() {
         // fileList.sort();
     }
     else {
+        showServerError("setFileList", response.status, text);
+        throw new Error("Can not get file list");
     }
 }