Add defensive check to GetRecurringJobIds to prevent null reference exception
#123
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In the
HangfireWorkflowScheduler, it is possible for theGetRecurringJobIdsmethod to throw a null reference exception, and I have observed this occurring when multiple instances have their triggers being updated after a workflow definition change at the same time, even with distributed locking set up in Elsa. I believe this will at least prevent the null reference exception; without this, the handler crashes and recurring jobs get left around.Below is a snippet from the Hangfire code that retrieves the list
https://github.com/HangfireIO/Hangfire/blob/eb994c324c0ed2687e2c35412c72460a1c1f9e71/src/Hangfire.Core/Storage/StorageConnectionExtensions.cs#L75
And the
GetRecurringJobDtosmethod can definitely return objects without aJobset.https://github.com/HangfireIO/Hangfire/blob/eb994c324c0ed2687e2c35412c72460a1c1f9e71/src/Hangfire.Core/Storage/StorageConnectionExtensions.cs#L89