Make file upload safer

src/app/editor.js

@@ -27,12 +27,12 @@ function Editor (loadingFromGist, storage) {
 
   this.uploadFile = function (file, callback) {
     var fileReader = new FileReader();
-
     var cacheName = utils.fileKey(file.name);
+
     fileReader.onload = function (e) {
+      storage.set(cacheName, e.target.result);
+      sessions[cacheName] = null;
       SOL_CACHE_FILE = cacheName;
-      storage.set(SOL_CACHE_FILE, e.target.result);
-      sessions[SOL_CACHE_FILE] = null;
       callback();
     };
     fileReader.readAsText(file);