fix

src/controller.py

@@ -12,6 +12,7 @@ __TOPIC_TEXT__ = ""
 
 class Controller:
     connected = False
+	self.display = None
 
     def __init__(self, base_topic, mqtt_host, mqtt_port = 1883):
 
@@ -86,10 +87,10 @@ class Controller:
       while run:
           self.mqtt.loop()
 
-		
-          self.display.print(self.text[poscount])
-          poscount += 1
-          poscount %= len(self.text)
+		  if self.display is not None:
+            self.display.print(self.text[self.poscount])
+            self.poscount += 1
+            self.poscount %= len(self.text)
             time.sleep(self.scroll_interval)