Deferred execution duplicate index (MongoDB) error

[stefan-buys]

Describe the bug
When making use of the deferred execution (as demo'd in https://github.com/danielgerlag/workflow-core/tree/master/src/samples/WorkflowCore.Sample05),

e.g.
return ExecutionResult.Sleep(pollingDelay, new object());

I notice the following error (log):
A write operation resulted in an error. WriteError: { Category : "DuplicateKey", Code : 11000, Message : "E11000 duplicate key error collection: foobar.wfc.scheduled_commands index: idx_key dup key: { CommandName: "ProcessWorkflow", Data: "619cefda1e173f3b8cc532be" }" }.

To Reproduce
Run multiple hosts (6 at the moment) using MongoDB persistence; RedisLocking, RediseQueues and RedisEventHub. Defer the execution for an activity (as instructed at https://github.com/danielgerlag/workflow-core/tree/master/src/samples/WorkflowCore.Sample05).

When the activity is deferred, an error is logged out every 10 seconds.

Expected behavior
Activity should be delayed/deferred, execute and no errors be highlighted in logs

Additional context
running WorkflowCore 3.6.1

[potatopeelings]

@stefan-buys I ran into the same issue. There is a catch that never triggers because exception type is incorrect.

@danielgerlag I've raised a PR. I couldn't find any repo specific guidelines so I just raised a PR from the fork and put the issue number in there. Happy to modify if I flubbed up something. Cheers!