Stop interference again

crafter.lua

@@ -77,7 +77,8 @@ end
 while true do
     util.processMessage(function(m) 
         if m.cmd and m.item and m.cmd == "craft" then
-            return craft(m.item)
+            return true, craft(m.item)
         end
+        return false
     end)
 end

server.lua

@@ -137,7 +137,7 @@ function processRequests()
             local ok, r = pcall(processRequest, msg)
             if not ok then r = "ERROR" end
 
-            return r
+            return true, r
         end)
     end
 end

util.lua

@@ -106,8 +106,8 @@ local function split(str, sSeparator, nMax, bRegexp)
 local function processMessage(f)
 	local id, msg = rednet.receive "dragon"
 	if msg and msg.uid then
-		local r = f(msg)
-		rednet.send(id, { uid = msg.uid, msg = r }, "dragon")
+		local send, response = f(msg)
+		if send then rednet.send(id, { uid = msg.uid, msg = response }, "dragon") end
 	end
 end