F# Invoke Timer doesn't work due to reflection w/ System.Threading.Tasks.Task

[LukePammant]

Expected Behavior

I should be able to register a Timer in an F# Actor and have it call the appropriate method.

Actual Behavior

The dotnet sdk throws an error on ValidateTimerCallback.

The first error occurs on Actor.cs ln:335 is:
Timer callback method: {callback} does not exist in the Actor class: {actorTypeName}
This can be worked around by prefixing the method name (callback argument) with "get_". For example the Tick method must be registered to the timer as get_Tick.

The second error is when validating that the return type is a Task. Even if the method just returns Task.CompletedTask this line will throw an error saying that the return type is not a task.

When I inspect the ReturnType while debugging I see that the F# Task is: Microsoft.FSharp.Core.FSharpFunc``2[[Microsoft.FSharp.Core.Unit, FSharp.Core, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a],[System.Threading.Tasks.Task, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], FSharp.Core, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

If I remove the Validation function I run into an exception on this line when it tries to cast the method call into a Task:

The tick method can be invoked via the dotnet sdk without issues via:
(POST {{daprUrl}}/v1.0/actors/MyActor/myactorid/method/Tick)

Maybe the dotnet sdk can fall back to calling the method the same way the InvokeMethod does without trying to cast the method to a Task?
DispatchInternalAsync does work when invoking the method
DispatchWithoutRemoting

Steps to Reproduce the Problem

From an F# actor call the Start method:
(POST {{daprUrl}}/v1.0/actors/MyActor/myactorid/method/Start)
member this.Start() = task { do! this.RegisterTimerAsync( "Tick", "get_Tick", null, TimeSpan.FromMilliseconds(float 1000), TimeSpan.FromMilliseconds(float 1000) ) |> Async.AwaitTask |> Async.Ignore } :> Task

The tick method can be:
member this.Tick() = Task.CompletedTask

Release Note

RELEASE NOTE:

[rynowak]

Do you have your sample pushed somewhere I can? (To see the workaround) InvokeMethod I think does require the return type to be a Task.

@cartermp FYI

[LukePammant]

@rynowak - master...LukePammant:fsharp-actor-timers heres the simple change that got the timer function to fire off. Its just a copy paste of the DispatchWithoutRemotingAsync method. Regardless it looks like it just assigns the result of the method.Invoke() to dynamic and only calls .GetAwaiter().GetResult() if the dynamic type is a Task. If its not a Task it returns default.

Since this is for a timer job the result doesn't really matter but would this swallow any potential errors since it doesn't await the F# Task and simply returns default? I should have some time over the weekend to experiment a little more.