bugfix: ensure packet_get_payload returns null when packet_get_payload_len is 0

src/packet/packet_utils.cpp

@@ -468,7 +468,15 @@ const char *packet_get_payload(const struct packet *pkt)
     {
         return NULL;
     }
-    return pkt->layers[pkt->layers_used - 1].pld_ptr;
+
+    if (pkt->layers[pkt->layers_used - 1].pld_len)
+    {
+        return pkt->layers[pkt->layers_used - 1].pld_ptr;
+    }
+    else
+    {
+        return NULL;
+    }
 }
 
 uint16_t packet_get_payload_len(const struct packet *pkt)