Fixed negative sleep_time error

Calendar/LoopTimer.py

@@ -1,5 +1,7 @@
 from datetime import datetime, timedelta
 
+min_sleep_minutes = 0
+
 class LoopTimer (object):
     """Manages loop times and sleeps until
     next loop."""
@@ -36,6 +38,9 @@ class LoopTimer(object):
             time_until_hour = self.get_time_to_next_hour()
             if time_until_hour < sleep_time:
                 return time_until_hour
+
+        if sleep_time < timedelta(0):
+            sleep_time = timedelta(0, 0, 0, 0, min_sleep_minutes)
         return sleep_time
 
     def get_last_duration (self):