V3 Login throws Exception when Username or Password is null

Issue and how to reproduce

create instance of Elsa Server and Elsa Studio (I am using Blazor Server)
go to login
leave username and/or password empty
press login
be sad because Exception

What is happening behind the scenes?

Elsa Studio calls the Elsa server's Login Endpoint.

The Endpoint receives a (Login)Request containg username and password. There is no validation being executed to check the values for null.

The endpoint starts out by calling .Trim() on the input values. This results in a NullReferenceException and a StatusCode 500.

    public override async Task<LoginResponse> ExecuteAsync(Request request, CancellationToken cancellationToken)
    {
        var user = await _userCredentialsValidator.ValidateAsync(request.Username.Trim(), request.Password.Trim(), cancellationToken);
        ...

Solution(?)

The Endpoint is built using FastEndpoints. While I am personally not familiar with this framework, I assume that adding a validator should not be too hard.

Additionally, input validation should also be implemented on the client side, providing feedback directly in the ui.

Proceeding-Proposal

As I am a backend engineer, I will take a look on the server side.

Also, as a backend engineer, my UIs may often be functional, though usually not very pretty. Hence, I would appreciate if someone with more UI skills than me, could help out with this :)

Note

I am using following versions:

      <PackageReference Include="Elsa" Version="3.0.0-preview.727" />
      <PackageReference Include="Elsa.Identity" Version="3.0.0-preview.727" />
      <PackageReference Include="Elsa.Workflows.Api" Version="3.0.0-preview.727" />

and

      <PackageReference Include="Elsa.Studio" Version="3.0.0-preview.94" />
      <PackageReference Include="Elsa.Studio.Core.BlazorServer" Version="3.0.0-preview.94" />
      <PackageReference Include="Elsa.Studio.Login.BlazorServer" Version="3.0.0-preview.94" />

elsa-workflows / elsa-core