catch exceptions in loadData().

dream/platform/static/src/dream_launcher.js

@@ -236,6 +236,11 @@
     });
 
     var loadData = function (data) {
+      dream_instance.clearAll();
+      $('#graph_zone').hide();
+      $('#spreadsheet_output').hide();
+
+      try {
         // spreadsheet
         var spreadsheet_data = data.spreadsheet;
         if (spreadsheet_data !== undefined) {
@@ -277,6 +282,9 @@
         } else {
           dream_instance.redraw();
         }
+      } catch (e) {
+	alert('Loading data failed.');
+      }
     };
     // Check if there is already data when we first load the page, if yes, then build graph from it
     jio.get({
@@ -461,7 +469,6 @@
     $("#import_file").change(function () {
       var form = $(this).parent('form')[0];
       var form_data = new FormData(form);
-      dream_instance.clearAll();
       $.ajax('/postJSONFile', {
         type: 'POST',
         contentType: false,