[round_robin] Do not crash on invalid duty start dates (#2301)

bugbot/round_robin.py

@@ -12,7 +12,12 @@
 from bugbot import logger, utils
 from bugbot.components import Components
 from bugbot.people import People
-from bugbot.round_robin_calendar import BadFallback, Calendar, InvalidCalendar
+from bugbot.round_robin_calendar import (
+    BadFallback,
+    Calendar,
+    InvalidCalendar,
+    InvalidDateError,
+)
 
 
 class RoundRobin(object):
@@ -77,7 +82,7 @@ def feed(self, teams: Set[str] | None = None) -> None:
 
                     self.data[component_name] = calendar
 
-            except (BadFallback, InvalidCalendar) as err:
+            except (BadFallback, InvalidCalendar, InvalidDateError) as err:
                 logger.error(err)
                 # If one the team's calendars failed, it is better to fail loud,
                 # and disable all team's calendars.

bugbot/round_robin_calendar.py

@@ -10,6 +10,7 @@
 
 import recurring_ical_events
 import requests
+from dateutil.parser import ParserError
 from dateutil.relativedelta import relativedelta
 from icalendar import Calendar as iCalendar
 from libmozdata import utils as lmdutils
@@ -26,6 +27,10 @@ class BadFallback(Exception):
     pass
 
 
+class InvalidDateError(ParserError):
+    """Raised when a date in a rotation calendar is invalid"""
+
+
 class Calendar:
     def __init__(self, fallback, team_name, people=None):
         self.people = People.get_instance() if people is None else people
@@ -108,7 +113,12 @@ def __init__(self, cal, fallback, team_name, people=None):
         super().__init__(fallback, team_name, people=people)
         start_dates = cal.get("duty-start-dates", {})
         if start_dates:
-            dates = sorted((lmdutils.get_date_ymd(d), d) for d in start_dates.keys())
+            try:
+                dates = sorted((lmdutils.get_date_ymd(d), d) for d in start_dates)
+            except ParserError as err:
+                raise InvalidDateError(
+                    f"Invalid duty start date for the {team_name} team: {err}"
+                ) from err
             self.set_team(
                 list(start_dates[d] for _, d in dates), cal.get("triagers", {})
             )