_ZefyrLineState.bringIntoView error

main.dart

import 'package:flutter/material.dart';
import 'package:quill_delta/quill_delta.dart';
import 'package:zefyr/zefyr.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final pageController = PageController(initialPage: 0);
  var pageTitles = [
    'page_1',
    'page_2',
    'page_3',
    'page_4',
    'page_5',
    'page_6',
    'page_7',
    'page_8',
  ];
  var pageTexts = [
    'one\n',
    'two\n',
    'three\n',
    'four\n',
    'five\n',
    'six\n',
    'seven\n',
    'eight\n',
  ];
  final kDuration = Duration(milliseconds: 250);
  final kCurve = Curves.linear;

  @override
  Widget build(BuildContext context) {
    final showError = true;

    if (!showError) {
      // For me, anything more than 6 elements throws
      pageTitles = pageTitles.take(5);
      pageTexts = pageTitles.take(5);
    }

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          actions: [
            IconButton(
              icon: Icon(Icons.arrow_back),
              onPressed: () => pageController.animateToPage(
                0,
                duration: kDuration,
                curve: kCurve,
              ),
            ),
            IconButton(
              icon: Icon(Icons.arrow_forward),
              onPressed: () => pageController.animateToPage(
                pageTitles.length,
                duration: kDuration,
                curve: kCurve,
              ),
            )
          ],
        ),
        body: SafeArea(
          child: PageView.builder(
            controller: pageController,
            itemCount: pageTitles.length,
            itemBuilder: (_, i) {
              final title = pageTitles[i];
              final text = pageTexts[i];

              return Page(key: ValueKey(title), title: title, text: text);
            },
          ),
        ),
      ),
    );
  }
}

class Page extends StatefulWidget {
  Page({Key key, this.title, this.text}) : super(key: key);

  final String title;
  final String text;

  @override
  _PageState createState() => _PageState();
}

class _PageState extends State<Page> {
  ZefyrController textController;
  final textFocusNode = FocusNode();

  @override
  void dispose() {
    textController.dispose();
    textFocusNode.dispose();

    super.dispose();
  }

  @override
  void initState() {
    final Delta delta = Delta()..insert(widget.text);
    textController = ZefyrController(NotusDocument.fromDelta(delta));
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return ZefyrScaffold(
      child: Column(
        children: [
          Text(widget.title),
          ZefyrField(
            height: 200.0,
            controller: textController,
            focusNode: textFocusNode,
          )
        ],
      ),
    );
  }
}