Catch error state

homeassistant/components/sensor/dweet.py

@@ -85,13 +85,13 @@ class DweetSensor(Entity):
     @property
     def state(self):
         """ Returns the state. """
-        values = json.dumps(self.dweet.data[0]['content'])
-        if values is not None:
+        if self.dweet.data is None:
+            return STATE_UNKNOWN
+        else:
+            values = json.dumps(self.dweet.data[0]['content'])
             value = template.render_with_possible_json_value(
                 self.hass, self._value_template, values)
             return value
-        else:
-            return STATE_UNKNOWN
 
     def update(self):
         """ Gets the latest data from REST API. """
@@ -104,7 +104,7 @@ class DweetData(object):
 
     def __init__(self, device):
         self._device = device
-        self.data = dict()
+        self.data = None
 
     @Throttle(MIN_TIME_BETWEEN_UPDATES)
     def update(self):