ErrorException: Undefined array key 0

[fantasycalendar-sentry-integration]

Sentry Issue: FANTASY-CALENDAR-8

ErrorException: Undefined array key 0
  File "/app/Services/EpochService/Processor/State.php", line 313, in App\Services\EpochService\Processor\State::isNumbered
    return $this->currentMonth()->daysInYear[$this->day-1]->isNumbered;
  File "/app/Services/EpochService/Processor/State.php", line 111, in App\Services\EpochService\Processor\State::toArray
    'isNumbered' => $this->isNumbered(),
  File "/app/Services/EpochService/Processor.php", line 108, in App\Services\EpochService\Processor::stepForward
    $this->epochs->insertFromArray($this->state->toArray());
  File "/app/Services/EpochService/Processor.php", line 59, in App\Services\EpochService\Processor::processUntil
    $this->stepForward();
  File "/app/Services/EpochService/Processor.php", line 88, in App\Services\EpochService\Processor::processUntilDate
    });
...
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