loadingWidget property

Widget to display while waiting for the first chunk from the stream.

This widget is shown when the stream hasn't emitted any data yet. Once the first chunk arrives, this widget is replaced with the rendered markdown content.

If not provided, an empty invisible container is shown (SizedBox.shrink).

Example:

loadingWidget: Center(
  child: Column(
    mainAxisAlignment: MainAxisAlignment.center,
    children: [
      CircularProgressIndicator(),
      SizedBox(height: 16),
      Text('Loading content...'),
    ],
  ),
)