old_contents: from django.utils import timezone
  
  
  def get_requested_time(request):
      query = request.GET
      month, year = query.get('month', None), query.get('year', None)
  
      if month and year:
          return timezone.datetime(year=int(year), month=int(month), day=1)
      else:
          return None
  
new_contents: from django.utils import timezone
  
  
  def get_requested_time(request):
      query = request.GET
      month, year = query.get('month', None), query.get('year', None)
  
      if month and year:
          try:
              return timezone.datetime(year=int(year), month=int(month), day=1)
          except ValueError:
              pass
      return None
  
subject: Fix handling of invalid parameters