Dart 错误：无法调用需要 const 表达式的非const构造函数

我以"BottomNavigationBar"为例来构建我的应用程序.我曾try 实现如下的RaisedButton:

      child: Container(
        child: Column(
          children: <Widget>[
            RaisedButton(
              child: Text('Montag'),
            )
          ],
        ),
      ),
    ), 

并获得以下错误消息:

lib/main.dart:48:16: Error: Cannot invoke a non-'const' constructor where a const expression is expected.
Try using a constructor or factory that is 'const'.
       child: Column(
              ^^^^^^
lib/main.dart:47:14: Error: Cannot invoke a non-'const' constructor where a const expression is expected.
Try using a constructor or factory that is 'const'.
     child: Container(
            ^^^^^^^^^

我能做什么？

编辑:应要求，以下是更多代码:

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
  TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static const List<Widget> _widgetOptions = <Widget>[
    Text(
      'Index 0: Startseite',
      style: optionStyle,
    ),
    const Center(
      child: const Container(
        child: Column(
          children: <Widget>[
            RaisedButton(
              child: Text('Montag'),
            )
          ],
        ),
      ),
    ),
    const WebView(
      initialUrl: 'mygoogledrivelink',
      javascriptMode: JavascriptMode.unrestricted,
    ),
  ];