Better handling if invalid known_devices.csv encountered.

homeassistant/observers.py

@@ -89,8 +89,12 @@ class DeviceTracker(object):
 
         self.lock = threading.Lock()
 
+        # Dictionary to keep track of known devices and devices we track
         self.known_devices = {}
 
+        # Did we encounter a valid known devices file
+        self.invalid_known_devices_file = False
+
         # Read known devices if file exists
         if os.path.isfile(KNOWN_DEVICES_FILE):
             with open(KNOWN_DEVICES_FILE) as inp:
@@ -100,6 +104,7 @@ class DeviceTracker(object):
                 # so we can ensure we have unique categories.
                 used_categories = []
 
+                try:
                     for row in csv.DictReader(inp):
                         device = row['device']
 
@@ -127,6 +132,9 @@ class DeviceTracker(object):
                             self.known_devices[device]['category'] = category
                             used_categories.append(category)
 
+                except KeyError:
+                    self.invalid_known_devices_file = False
+                    self.logger.warning("Invalid {} found. We won't update it with new found devices.".format(KNOWN_DEVICES_FILE))
 
         if len(self.device_state_categories()) == 0:
             self.logger.warning("No devices to track. Please update {}.".format(KNOWN_DEVICES_FILE))
@@ -169,6 +177,8 @@ class DeviceTracker(object):
         self.statemachine.set_state(STATE_CATEGORY_ALL_DEVICES, all_devices_state)
 
         # If we come along any unknown devices we will write them to the known devices file
+        # but only if we did not encounter an invalid known devices file
+        if not self.invalid_known_devices_file:
             unknown_devices = [device for device in found_devices if device not in self.known_devices]
 
             if len(unknown_devices) > 0: