viewmodel ins wpf gepackt, build failed

DaSaSo.Wpf/ViewModel/Commands/AsyncCommandBase.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
+
+namespace DaSaSo.Wpf.ViewModel.Commands
+{
+    public abstract class AsyncCommandBase : ICommand
+    {
+        bool _isExecuting = false;
+        public event EventHandler? CanExecuteChanged;
+
+        public bool IsExecuting
+        {
+            get => _isExecuting;
+            set
+            {
+                _isExecuting = value;
+                CanExecuteChanged?.Invoke(this, new EventArgs());
+            }
+        }
+
+        protected void OnCanExecuteChanged()
+        {
+            CanExecuteChanged?.Invoke(this, new EventArgs());
+        }
+        
+
+        public virtual bool CanExecute(object? parameter)
+        {
+            return !IsExecuting;
+        }
+
+        public async void Execute(object? parameter)
+        {
+            IsExecuting = true;
+            await ExecuteAsync(parameter);
+            IsExecuting = false;
+        }
+
+        public abstract Task ExecuteAsync(object? parameter);
+    }
+}