call manager_event only if there is not null channel structure

(Closes issue ASTERISK-19298)
Reported by: robinfood
Patches:
        issue19298.patch uploaded by may213 (License #5415)
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Merged revisions 355136 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 355137 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@355138 65c4cc65-6c06-0410-ace0-fbb531ad65f3

addons/chan_ooh323.c

@@ -476,8 +476,11 @@ static struct ast_channel *ooh323_new(struct ooh323_pvt *i, int state,
 			} 
 	 	}
 
-		manager_event(EVENT_FLAG_SYSTEM, "ChannelUpdate", "Channel: %s\r\nChanneltype: %s\r\n"
+		if (ch) {
+			manager_event(EVENT_FLAG_SYSTEM, "ChannelUpdate", 
+				"Channel: %s\r\nChanneltype: %s\r\n"
 				"CallRef: %d\r\n", ast_channel_name(ch), "OOH323", i->call_reference);
+		}
 	} else
 		ast_log(LOG_WARNING, "Unable to allocate channel structure\n");