add pattern match for topic alias

Prior to this change, it assume that topic_alias exists defaultly
which may cause the unexpected bug

This change fix this bug above

src/emqx_protocol.erl

@@ -650,9 +650,15 @@ check_publish(Packet, PState) ->
 check_pub_caps(#mqtt_packet{header = #mqtt_packet_header{qos = QoS, retain = Retain},
                             variable = #mqtt_packet_publish{ properties = Properties}},
                #pstate{zone = Zone}) ->
-    #{'Topic-Alias' := TopicAlias} = Properties,
+    emqx_mqtt_caps:check_pub(Zone, #{qos => QoS, retain => Retain});
+check_pub_caps(#mqtt_packet{header = #mqtt_packet_header{qos = QoS, retain = Retain},
+                            variable = #mqtt_packet_publish{
+                                          properties = #{'Topic-Alias' := TopicAlias}
+                                         }},
+               #pstate{zone = Zone}) ->
     emqx_mqtt_caps:check_pub(Zone, #{qos => QoS, retain => Retain, topic_alias => TopicAlias}).
 
+
 check_pub_acl(_Packet, #pstate{is_super = IsSuper, enable_acl = EnableAcl})
     when IsSuper orelse (not EnableAcl) ->
     ok;