more error handling, fix indentation

routes/membership.js

@@ -31,7 +31,11 @@ function addNewMemberToSheets(data, callback) {
     function getInfoAndWorksheets(cb) {
       console.log('Start Google Spreadsheet info fetch.');
       doc.getInfo(function(err, info) {
+        if(err) {
+          cb(err);
+        } else {
           cb(null, info.worksheets[0]);
+        }
       });
     },
     function addRow(sheet, cb) {