[bug] Added in check for MySQL OperationalError for local development

[MICROBA-951]

When running the notify_credentials command locally there is an
OperationalError thrown by MySQL when there are no more results
available for the queryset iterator. This change catches that exception,
checks state, and then logs according to that state. This code runs in
production without issue. This changes allows for the code to be run
locally without a separate code path.

openedx/core/djangoapps/credentials/management/commands/notify_credentials.py

@@ -21,6 +21,7 @@ from datetime import datetime, timedelta
 import dateutil.parser
 from django.contrib.auth import get_user_model
 from django.core.management.base import BaseCommand, CommandError
+from MySQLdb import OperationalError
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
 from pytz import UTC
@@ -67,10 +68,24 @@ def paged_query(queryset, delay, page_size):
 
         if delay and page:
             time.sleep(delay)
+
         index = 0
-        for item in subquery.iterator():
-            index += 1
-            yield page_start + index, item
+        try:
+            for item in subquery.iterator():
+                index += 1
+                yield page_start + index, item
+        except OperationalError:
+            # When running the notify_credentials command locally there is an
+            # OperationalError thrown by MySQL when there are no more results
+            # available for the queryset iterator. This change catches that exception,
+            # checks state, and then logs according to that state. This code runs in
+            # production without issue. This changes allows for the code to be run
+            # locally without a separate code path.
+            if index == count:
+                log.info('OperationalError Exception caught, all known results processed in paged_query')
+            else:
+                log.warning('OperationalError Exception caught, it is possible some results were missed')
+            continue
 
 
 class Command(BaseCommand):
@@ -246,6 +261,7 @@ class Command(BaseCommand):
         """ Run actual handler commands for the provided certs and grades. """
 
         course_cert_info = {}
+
         # First, do certs
         for i, cert in paged_query(certs, delay, page_size):
             if site_config and not site_config.has_org(cert.course_id.org):