Connection: fix modifiers assignment for fetch()

lib/Connection.js

@@ -655,7 +655,10 @@ Connection.prototype._fetch = function(which, uids, options) {
   fetching.push('FLAGS');
   fetching.push('INTERNALDATE');
 
+  var modifiers;
+
   if (options) {
+    modifiers = options.modifiers;
     if (options.struct)
       fetching.push('BODYSTRUCTURE');
     if (options.size)
@@ -676,8 +679,7 @@ Connection.prototype._fetch = function(which, uids, options) {
 
   cmd += ')';
 
-  var modifiers = options.modifiers,
-      modkeys = (typeof modifiers === 'object' ? Object.keys(modifiers) : []),
+  var modkeys = (typeof modifiers === 'object' ? Object.keys(modifiers) : []),
       modstr = ' (';
   for (i = 0, len = modkeys.length, key; i < len; ++i) {
     key = modkeys[i].toUpperCase();