Fixes UPS MyChoice exception (#9587)

* Fixes UPS MyChoice exception

* Added unit of measurement

* Collaborator-requested changes

homeassistant/components/sensor/ups.py

@@ -76,17 +76,26 @@ class UPSSensor(Entity):
         """Return the state of the sensor."""
         return self._state
 
+    @property
+    def unit_of_measurement(self):
+        """Return the unit of measurement of this entity, if any."""
+        return 'packages'
+
     def _update(self):
         """Update device state."""
         import upsmychoice
         status_counts = defaultdict(int)
-        for package in upsmychoice.get_packages(self._session):
-            status = slugify(package['status'])
-            skip = status == STATUS_DELIVERED and \
-                parse_date(package['delivery_date']) < now().date()
-            if skip:
-                continue
-            status_counts[status] += 1
+        try:
+            for package in upsmychoice.get_packages(self._session):
+                status = slugify(package['status'])
+                skip = status == STATUS_DELIVERED and \
+                    parse_date(package['delivery_date']) < now().date()
+                if skip:
+                    continue
+                status_counts[status] += 1
+        except upsmychoice.UPSError:
+            _LOGGER.error('Could not connect to UPS My Choice account')
+
         self._attributes = {
             ATTR_ATTRIBUTION: upsmychoice.ATTRIBUTION
         }