ErrorException: Attempt to read property "envelope" on null

[sentry-io]

Sentry Issue: APIARY-BB

ErrorException: Attempt to read property "envelope" on null
  File "/app/Observers/DocuSignEnvelopeObserver.php", line 17, in Illuminate\Foundation\Bootstrap\HandleExceptions::handleError
    $envelope->signable->envelope->count() === 0
  File "/app/Observers/DocuSignEnvelopeObserver.php", line 17, in App\Observers\DocuSignEnvelopeObserver::deleted
    $envelope->signable->envelope->count() === 0
  File "/app/Http/Middleware/CASAuthenticate.php", line 93, in App\Http\Middleware\CASAuthenticate::handle
    return $next($request);
  File "/app/Http/Middleware/Sentry.php", line 59, in App\Http\Middleware\Sentry::handle
    return $next($request);
  File "/public/index.php", line 52
    $request = Request::capture()
...
(84 additional frame(s) were not displayed)

[kberzinch]

occurred while soft-deleting an envelope