Merge pull request #1052 from jovanpreet/master

made XMPPIQ nullable as XMPPIDTracker returns null on timeout. This results in crash when accessing it.

Author: chrisballinger

Extensions/XEP-0313/XMPPMessageArchiveManagement.h

@@ -47,7 +47,7 @@ extern NSString *const XMLNS_XMPP_MAM;
 @optional
 - (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didFinishReceivingMessagesWithSet:(XMPPResultSet *)resultSet;
 - (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didReceiveMAMMessage:(XMPPMessage *)message;
-- (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didFailToReceiveMessages:(XMPPIQ *)error;
+- (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didFailToReceiveMessages:(nullable XMPPIQ *)error;
 
 - (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didReceiveFormFields:(XMPPIQ *)iq;
 - (void)xmppMessageArchiveManagement:(XMPPMessageArchiveManagement *)xmppMessageArchiveManagement didFailToReceiveFormFields:(XMPPIQ *)iq;