Fix problem with illegal offset error. (#226)

* Fix problem with illegal offset error. * Switched to more precise comparison method (type detection).

Author: szymekjanaczek

src/Connection/Protocols/ImapProtocol.php

@@ -600,7 +600,12 @@ public function fetch($items, $from, $to = null, $uid = IMAP::ST_UID) {
  } else if ($tokens[2][0] == 'UID') {
  $uidKey = 1;
  } else {
- $uidKey = array_search('UID', $tokens[2]) + 1;
+ $found = array_search('UID', $tokens[2]);
+ if ($found === false || $found === -1) {
+ continue;
+ }
+
+ $uidKey = $found + 1;
  }
  }