Land rapid7#4880: @wchen-r7 check if module has session before comparison

Author: Brent Cook

lib/msf/core/payload_set.rb

@@ -236,7 +236,7 @@ def find_payload(platform, arch, handler, session, payload_type)
       next if (handler and not p.handler_klass.ancestors.include?(handler))
 
       # Check to see if the session classes match.
-      next if (session and not p.session.ancestors.include?(session))
+      next if (session and p.session and not p.session.ancestors.include?(session))
 
       # Check for matching payload types
       next if (payload_type and p.payload_type != payload_type)