@model string
@{
    var fieldName = Model;
}
@if (ViewData.ModelState[fieldName] != null 
     && ViewData.ModelState[fieldName].Errors.Any())
{
        foreach (var error in ViewData.ModelState[fieldName].Errors)
        {
            <div id="@fieldName-error" class="is-invalid invalid-feedback">@error.ErrorMessage</div>
        }
}