Null reference exception on PopulateUnitList

[timbellomo]

Encountered the following while testing:

System.NullReferenceException: Object reference not set to an instance of an object.   
at Dievas.CAD.PopulateUnitList(IEnumerable`1 initialUnits) in D:\WebApplications\Dashboard\Dievas\CAD.cs:line 186   
at Dievas.Hubs.DashboardHub.AllUnits(IEnumerable`1 units) in D:\WebApplications\Dashboard\Dievas\Hubs\DashboardHub.cs:line 96   
at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.ExecuteMethod(ObjectMethodExecutor methodExecutor, Hub hub, Object[] arguments)   
at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.<>c__DisplayClass16_0.<<Invoke>g__ExecuteInvocation|0>d.MoveNext()

Was thought to be related to changes in branch 21-replace-index-of-with-findindex-for-adding-assignedunit-dto, but after being unable to reproduce locally, we ran a re-deploy, and the issue resolved.

Logging here in case the issue crops up again.