C#项目关于HRMsys.exe”不包含适合于入口点的静态“Main”方法

做项目练习时，不小心删除了文件

又添加了APP.xaml，运行出现了HRMsys.exe”不包含适合于入口点的静态“Main”方法问题

和以前做过的项目做对比，程序的如果地址在App.xaml中，而运行出错的显然没有程序口地址

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;

namespace Customerapp
{
    /// <summary>
    /// App.xaml 的交互逻辑
    /// </summary>
    public partial class App : Application
    {
    }
}

APP 转到定义，两段代码对比，一切尽在不言中。

namespace HRMsys.UI {

    /// <summary>
    /// App
    /// </summary>
    public partial class App : System.Windows.Application, System.Windows.Markup.IComponentConnector {

        private bool _contentLoaded;

        /// <summary>
        /// InitializeComponent
        /// </summary>
        [System.Diagnostics.DebuggerNonUserCodeAttribute()]
        [System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
        public void InitializeComponent() {

            #line 4 "..\..\App.xaml"
            this.StartupUri = new System.Uri("MainWindow.xaml", System.UriKind.Relative);

            #line default
            #line hidden
            if (_contentLoaded) {
                return;
            }
            _contentLoaded = true;
            System.Uri resourceLocater = new System.Uri("/HRMsys;component/app.xaml", System.UriKind.Relative);

            #line 1 "..\..\App.xaml"
            System.Windows.Application.LoadComponent(this, resourceLocater);

            #line default
            #line hidden
        }

        [System.Diagnostics.DebuggerNonUserCodeAttribute()]
        [System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
        [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Design", "CA1033:InterfaceMethodsShouldBeCallableByChildTypes")]
        [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
        [System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily")]
        void System.Windows.Markup.IComponentConnector.Connect(int connectionId, object target) {
            this._contentLoaded = true;
        }
    }
}

namespace Customerapp {

    /// <summary>
    /// App
    /// </summary>
    public partial class App : System.Windows.Application {

        /// <summary>
        /// InitializeComponent
        /// </summary>
        [System.Diagnostics.DebuggerNonUserCodeAttribute()]
        [System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
        public void InitializeComponent() {

            #line 4 "..\..\App.xaml"
            this.StartupUri = new System.Uri("MainWindow.xaml", System.UriKind.Relative);

            #line default
            #line hidden
        }

        /// <summary>
        /// Application Entry Point.
        /// </summary>
        [System.STAThreadAttribute()]
        [System.Diagnostics.DebuggerNonUserCodeAttribute()]
        [System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
        public static void Main() {
            Customerapp.App app = new Customerapp.App();
            app.InitializeComponent();
            app.Run();
        }
    }
}