Prevent submitting empty code

views/problem.ejs

@@ -202,6 +202,7 @@ editor.setShowPrintMargin(false);
 editor.renderer.updateFontSize();
 
 function submit_code() {
+  if (!editor.getValue().trim()) return false;
   $('#submit_code input[name=language]').val($('#languages-menu .item.active').data('value'));
   $('#submit_code input[name=code]').val(editor.getValue());
   return true;