ProgressTask accepts negative MaxValue without validation

[MateusMo]

Information

• OS: Ubuntu 24.04
• Version: main (current branch)
• Terminal: GNOME Terminal

Describe the issue

While exploring the progress API, I noticed that AddTask accepts a negative maxValue without any validation.

For example:

using Spectre.Console;

AnsiConsole.Progress()
    .Start(ctx =>
    {
        var task = ctx.AddTask("Loading World Map", true, -1);

        while (!ctx.IsFinished)
        {
            task.Increment(1);
            Thread.Sleep(50);
        }
    });

The task completes immediately and the progress output appears inconsistent.

While looking through the implementation, I noticed that GetPercentage() explicitly handles MaxValue == 0, but there doesn't seem to be any validation preventing negative values from being passed.

I'm not sure whether accepting negative values is intentional or if they should be rejected (for example by throwing ArgumentOutOfRangeException).

Expected behavior

If negative MaxValue values are not supported, it might be better to validate the argument early instead of allowing the task to enter an inconsistent state.

If this is considered a bug and the proposed direction makes sense, I'd be happy to work on a PR.

[Rain6435]

Hey Mateus. I took the time to look at your issue and in my opinion, it's a real design neglect. I took the time to investigate as well. I think that this should throw an argument exception in the case where maxValue is less than 0. I did write a quick solution to it(had time to kill).