В вашем коде у вас есть:
...
home: new Scaffold(
body: Center(
child: Text('works!'),
style: new TextStyle()
)
...
Но Центр класс не имеет свойства style:
/// A widget that centers its child within itself.
///
/// This widget will be as big as possible if its dimensions are constrained and
/// [widthFactor] and [heightFactor] are null. If a dimension is unconstrained
/// and the corresponding size factor is null then the widget will match its
/// child's size in that dimension. If a size factor is non-null then the
/// corresponding dimension of this widget will be the product of the child's
/// dimension and the size factor. For example if widthFactor is 2.0 then
/// the width of this widget will always be twice its child's width.
///
/// See also:
///
/// * [Align], which lets you arbitrarily position a child within itself,
/// rather than just centering it.
/// * [Row], a widget that displays its children in a horizontal array.
/// * [Column], a widget that displays its children in a vertical array.
/// * [Container], a convenience widget that combines common painting,
/// positioning, and sizing widgets.
/// * The [catalog of layout widgets](https://flutter.io/widgets/layout/).
class Center extends Align {
/// Creates a widget that centers its child.
const Center({ Key key, double widthFactor, double heightFactor, Widget child })
: super(key: key, widthFactor: widthFactor, heightFactor: heightFactor, child: child);
}
Итак, ошибка, показанная DartAnalyser, верна и ожидаема