Wrapping a call to `RuleForEach` with `WhenAsync` will trigger a `AsyncValidatorInvokedSynchronouslyException` even when calling `ValidateAsync.

[JeremySkinner]

FluentValidation version

11.0.2

ASP.NET version

No response

Summary

Wrapping a call to RuleForEach with WhenAsync will trigger a AsyncValidatorInvokedSynchronouslyException even when calling ValidateAsync.

The AsyncValidatorInvokedSynchronouslyException should only be thrown when calling Validate, never ValidateAsync.

Steps to Reproduce

class MyValidator : AbstractValidator<Person> {
  public MyValidator() {
    WhenAsync((x, cancel) => x.Id > 0, () => {
      RuleForEach(x => x.Nicknames).NotNull();
    });
  }
}

class Person {
  public int Id { get; set; }
  public string[] Nicknames { get; set; }
}

var validator = new MyValidator();
await validator.ValidateAsync(new Person());
// Incorrectly throws a AsyncValidatorInvokedSynchronouslyException even though it was invoked asynchronously. 

[JeremySkinner]

Fixed in 11.0.3