FIX: prosody: destroy_request check

resources/prosody-plugins/token/util.lib.lua

@@ -142,9 +142,10 @@ function Util:get_public_key(keyId)
             -- TODO: This check is racey. Not likely to be a problem, but we should
             --       still stick a mutex on content / code at some point.
             if code == nil then
-                -- no longer works in prosody 0.11
-                -- @TODO: work with prosody devs to determine better timeout mechanism for timing out active http requests
-                -- http.destroy_request(request);
+                -- no longer present in prosody 0.11, so cehck before calling
+                if http.destroy_request ~= nil then
+                    http.destroy_request(request);
+                end
                 done();
             end
         end