<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        
        <TextBox  Grid.Row="0"
           FontSize="14"       
           Text="{Binding InputNumber, 
           UpdateSourceTrigger=PropertyChanged,
           ValidatesOnDataErrors=True}"
           Width="70" Height="30"/>

        <Button Grid.Row="1" Width="70" Height="30"
                Command="{Binding PrintCommand}" />
        
    </Grid>
</Window>

public class ViewModel: BaseViewModel, IDataErrorInfo
    {
    public  RelayCommand PrintCommand { get; set; }

        #region Validation

        /// <summary>
        /// Хранение текста ошибок
        /// </summary>
        private Dictionary<string, string> errors = new Dictionary<string, string>();
        public string Error => throw new NotImplementedException();

        public string this[string columnName]
        {
            get
            {
                if (errors.ContainsKey(columnName))
                    return errors[columnName];
                return null;
            }
        }

        private void ValidateProperty([CallerMemberName] string propertyName = null)
        {
            var propValObj = this.GetType().GetProperty(propertyName).GetValue(this, null);

            if (propValObj is int propVal)
            {
                if (propVal == 0)
                {
                    errors.TryAdd(propertyName, "Error");
                }
                else
                {
                    errors.Remove(propertyName);
                }
            }
            PrintCommand.RaiseCanExecuteChanged();
        }
        #endregion

        private int _inputNumber;

        public int InputNumber
	{
	   get { return _inputNumber; }
	   set { _inputNumber = value; ValidateProperty(); }
	}

	public ViewModel()
	{
	PrintCommand = new RelayCommand((_)=>CustomCommand(),()=> CanCommandExecute());
	}

	private bool CanCommandExecute()
	{
            return !errors.Any();
        }

	private void CustomCommand(){}
}