[Components] Generic nested component with EventCallback<T> throws compiler error

[mwinkler]

Describe the bug

A self nested component with a generic parameter and a EventCallback throws a compilation error:

CS1660 Cannot convert lambda expression to type 'EventCallback<TItem>' because it is not a delegate type

Tree.razor:

@typeparam TItem

<Tree bind-Value="@Value" />

@functions {
    [Parameter] TItem Value { get; set; }
    [Parameter] EventCallback<TItem> ValueChanged { get; set; }
}

I know this component would create a infinite render loop, but this is only for demonstration purpose.

To Reproduce

Steps to reproduce the behavior:

1. Create new razor component project
2. Create new Tree.razor component
3. Paste above code
4. Build
5. See error

Additional context

.NET Core SDK (reflecting any global.json):
Version: 3.0.100-preview3-010431
Commit: d72abce213

Runtime Environment:
OS Name: Windows
OS Version: 10.0.16299
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.0.100-preview3-010431\

Host (useful for support):
Version: 3.0.0-preview3-27503-5
Commit: 3844df9537

.NET Core SDKs installed:
2.1.202 [C:\Program Files\dotnet\sdk]
2.1.505 [C:\Program Files\dotnet\sdk]
2.1.600 [C:\Program Files\dotnet\sdk]
2.1.601 [C:\Program Files\dotnet\sdk]
2.1.602 [C:\Program Files\dotnet\sdk]
2.2.103 [C:\Program Files\dotnet\sdk]
3.0.100-preview3-010431 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0-preview3-19153-02 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0-preview3-27503-5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.0.0-preview3-27504-2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[rynowak]

Thanks @mwinkler - this was a known issue in preview 3. This will be fixed in the next release.