例外：调用节点模块失败，错误：错误：未捕获（在承诺中）：TypeError：无法读取属性＆＃39;添加＆＃39;未定义的

Question

我正在构建一个角度2项目。一旦我在我的html文件上改变了一些东西。例如，我想创建一个下拉导航栏。而这个错误不断出现。

异常：调用节点模块失败并显示错误：错误：未捕获（在承诺中）：TypeError：无法读取属性＆＃39;添加＆＃39;未定义的 TypeError：无法读取属性＆＃39;添加＆＃39;未定义的

我在更改代码时因某种原因修复了它。但是，当我再次改变时，它表明了。我的navbar.component.html看起来像这样。问题是第三个问题＆＃39;报告＆＃39;我想创建一个下拉导航栏。

    <meta http-equiv="pragma" content="no-cache" />
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-
    alpha.6/css/bootstrap.min.css" rel="stylesheet">
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
<div class='main-nav'>
    <div class='navbar navbar-inverse'>
        <div class='navbar-header'>
            <a class='navbar-brand' [routerLink]="['/home']">Angular</a>
            <button type='button' class='navbar-toggle' data-toggle='collapse' data-target='.navbar-collapse'>
                <span  (click)="isCollapsed = !isCollapsed">Toggle navigation</span>
                <span class='icon-bar'></span>
                <span class='icon-bar'></span>
                <span class='icon-bar'></span>
                <span class='icon-bar'></span>
            </button>
        </div>
        <div class='clearfix'></div>
        <div class='navbar-collapse collapse' >
                <ul class='nav navbar-nav navbar-right'>
                    <li [routerLinkActive]="['link-active']">
                        <a [routerLink]="['/home']">
                            <span class='glyphicon glyphicon-home'></span> Home
                        </a>
                    </li>
                    <li [routerLinkActive]="['link-active']">
                        <a [routerLink]="['/login']">
                            <span class='glyphicon glyphicon-th-list'></span> Log In
                        </a>
                    </li>
                    <li class="dropdown">
                        <a class="dropdown-toggle glyphicon glyphicon-th-list" data-toggle="dropdown">Report <!--[routerLink]="['/margin']"-->
                         </a>
                            <!--<span class='glyphicon glyphicon-th-list'></span>Report-->
                        <!--</a>-->
                        <ul class="dropdown-menu">
                            <li [routerLinkActive]="['link-active']"><a [routerLink]="['/margin']">Margin Report</a></li>
                            <li><a>Report 1</a></li>
                            <li><a>Report 2</a></li>
                        </ul>
                    </li>
                </ul>
</div>
    </div>
</div>

有谁知道这个问题？这真烦人..