Fix to pickle error and Nonetype comparison

fifo/__init__.py

@@ -1,5 +1,15 @@
+import sys
+
 from .fifo import FIFO
 
+# Applying fix from: https://github.com/Azure/azure-functions-python-worker/issues/640
+# [Fix] Create a wrapper for importing imgres
+from .date_trigger import *
+from . import CustomDateTrigger
+
+# [Fix] Register imgres into system modules
+sys.modules["CustomDateTrigger"] = CustomDateTrigger
+
 
 async def setup(bot):
     cog = FIFO(bot)

fifo/date_trigger.py

@@ -4,4 +4,7 @@ from apscheduler.triggers.date import DateTrigger
 class CustomDateTrigger(DateTrigger):
     def get_next_fire_time(self, previous_fire_time, now):
         next_run = super().get_next_fire_time(previous_fire_time, now)
-        return next_run if next_run >= now else None
+        return next_run if next_run is not None and next_run >= now else None
+
+    def __getstate__(self):
+        return {"version": 1, "run_date": self.run_date}