Problem when changing date in app, set state in flutter

Question

When clicking to change the date returns the error, how can I solve this?

exemple https://pub.dev/packages/flutter_calendar_week/example

I'm trying to use an example in my code, when I click

onDatePressed: (DateTime datetime) {
                    // Do something

                    setState(() {});

                  },

returns an error of cotroller.hasCliente == false

note_list_screen.dart

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter_notes/helper/note_provider.dart';
import 'package:flutter_notes/screens/note_edit_screen.dart';
import 'package:flutter_notes/utils/constants.dart';
import 'package:flutter_notes/widgets/list_item.dart';
import 'package:intl/intl.dart';
import 'package:provider/provider.dart';
import 'package:url_launcher/url_launcher.dart';
import 'package:flutter_calendar_week/flutter_calendar_week.dart';

class NoteListScreen extends StatelessWidget {
@override
Widget build(BuildContext context) => MaterialApp(
    title: 'CalendarWeek Example',
    home: HomePage(),
  );
   }

  class HomePage extends StatefulWidget {
@override
_HomePageState createState() => _HomePageState();
 }

 class _HomePageState extends State<HomePage> {
 final CalendarWeekController _controller = CalendarWeekController();

 @override
 Widget build(BuildContext context) {
 return FutureBuilder(
  future: Provider.of<NoteProvider>(context, listen: false).getNotes(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return Scaffold(
        body: Center(
          child: CircularProgressIndicator(),
        ),
      );
    } else {
      if (snapshot.connectionState == ConnectionState.done) {
        return Scaffold(
          body: Consumer<NoteProvider>(
            child: noNotesUI(context),
            builder: (context, noteprovider, child) =>
                noteprovider.items.length <= 0
                    ? child
                    : ListView.builder(
                        physics: BouncingScrollPhysics(),
                        itemCount: noteprovider.items.length + 1,
                        itemBuilder: (context, index) {
                          if (index == 0) {
                            return header();
                          } else {
                            final i = index - 1;
                            final item = noteprovider.items[i];

                            return ListItem(
                              item.id,
                              item.title,
                              item.content,
                              item.imagePath,
                              item.date,
                            );
                          }
                        },
                      ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: () {
              goToNoteEditScreen(context);
              // _controller.jumpToDate(DateTime.now());
            },
            child: Icon(Icons.add),
          ),
          bottomNavigationBar: BottomNavigationBar(
            currentIndex: 0,
            items: [
              BottomNavigationBarItem(
                  icon: Icon(Icons.person), title: Text("Minha conta")),
              BottomNavigationBarItem(
                  icon: Icon(Icons.calendar_today),
                  title: Text("Calendário")),
              BottomNavigationBarItem(
                  icon: Icon(Icons.favorite), title: Text("Favoritos")),
            ],
          ),
        );
       }
       }
         return Container();
        },
         );
          }

     Widget header() {
       return GestureDetector(
     onTap: _launchUrl,
        child: Container(
    decoration: BoxDecoration(
      color: headerColor,
      borderRadius: BorderRadius.only(
        bottomRight: Radius.circular(65.0),
      ),
    ),
    height: 270.0,
    width: double.infinity,
    child: Column(
      // COLUNA PRINCIPAL
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: [
        Expanded(
            flex: 3,
            child: Padding(
                padding: const EdgeInsets.all(30),
                child: Container(
                    color: headerColor,
                    child: Column(children: [
                      Row(
                        //LINHAA
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          Icon(
                            Icons.apps_sharp,
                            color: white,
                            size: 35,
                          ),
                          Text(
                            ' Fev',
                            style: TextStyle(
                                color: Colors.white, fontSize: 30),
                          ),
                          Icon(
                            Icons.notifications,
                            color: white,
                            size: 35,
                          ),
                        ],
                        //),
                      ),

                      SizedBox(height: 20),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          Text(
                            'Olá Thiago',
                            style: TextStyle(
                                color: Colors.white, fontSize: 30),
                          ),
                          Text(
                            '1 Lembrete Hoje',
                            style: TextStyle(
                                color: Colors.white, fontSize: 15),
                          ),
                        ],
                      ),
                      //  SizedBox(height: 1),
                      SizedBox(height: 1),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          //create calendar
                          // Icon(Icons.calendar_today, color: Colors.white, size: 35,),
                        ],
                      ),

                      SizedBox(height: 10),
                      CalendarWeek(
                        controller: _controller,
                        height: 100,
                        showMonth: true,
                        minDate: DateTime.now().add(
                          Duration(days: -365),
                        ),
                        maxDate: DateTime.now().add(
                          Duration(days: 365),
                        ),
                        onDatePressed: (DateTime datetime) {
                          // Do something

                          setState(() {});
                        },
                        onDateLongPressed: (DateTime datetime) {
                          //  _controller.jumpToDate(DateTime.now());
                          // Do something
                        },
                        onWeekChanged: () {
                          // Do something
                        },
                        decorations: [
                          DecorationItem(
                              decorationAlignment:
                                  FractionalOffset.bottomRight,
                              date: DateTime.now(),
                              decoration: Icon(
                                Icons.today,
                                color: Colors.blue,
                              )),
                          DecorationItem(
                              date: DateTime.now().add(Duration(days: 3)),
                              decoration: Text(
                                '', //feriado
                                style: TextStyle(
                                  color: Colors.brown,
                                  fontWeight: FontWeight.w600,
                                ),
                              )),
                        ],
                      ),
                      Expanded(
                        child: Center(
                          child: Text( 
      '${_controller.selectedDate.day}/
          ${_controller.selectedDate.month}/${_controller.selectedDate.year 
           }',
                            style: TextStyle(fontSize: 30),
                          ),
                        ),
                      )
                    ])))),
      ],
           ),
          ),
         );
        }

         void _launchUrl() async {
       const url = 'https://www.androidride.com';
           if (await canLaunch(url)) {
         await launch(url);
          } else {
       throw 'Could not launch $url';
         }
            }

         Widget noNotesUI(BuildContext context) {
       return ListView(
   children: [
    header(),
    Column(
      children: [
        Padding(
          padding: const EdgeInsets.only(top: 50.0),
          child: Image.asset(
            'img/Tasks.png',
            fit: BoxFit.scaleDown,
            width: 190.0,
            height: 180.0,
          ),
        ),
        RichText(
          text: TextSpan(style: noNotesStyle, children: [
            TextSpan(text: ' Nenhum lembrete adicionado \n Clica em "'),
            TextSpan(
                text: '+',
                style: boldPlus,
                recognizer: TapGestureRecognizer()
                  ..onTap = () {
                    goToNoteEditScreen(context);
                  }),
            TextSpan(text: '" para adicionar um lembrete')
          ]),
         ),
         ],
          ),
         ],
       );
     }

       void goToNoteEditScreen(BuildContext context) {
         Navigator.of(context).pushNamed(NoteEditScreen.route);
          }
      }

CALENDARWEEK.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_calendar_week/src/models/decoration_item.dart';
import 'package:flutter_calendar_week/src/models/week_item.dart';
import 'package:flutter_calendar_week/src/date_item.dart';
import 'package:flutter_calendar_week/src/utils/find_current_week_index.dart';
import 'package:flutter_calendar_week/src/utils/separate_weeks.dart';
import 'package:flutter_calendar_week/src/utils/compare_date.dart';

import 'package:flutter_calendar_week/src/strings.dart';
import 'package:flutter_calendar_week/src/utils/cache_stream.dart';

class CalendarWeekController {

  /// Today date time
 DateTime _today = DateTime.now();

 /// Store hast attach to a client state
 bool _hasClient = false;

 /// Return [true] if attached to [CalendarWeek] widget
 bool get hasClient => _hasClient;

 /// Store a selected date
 DateTime? _selectedDate;

 /// Get [_selectedDate] selected;
 DateTime get selectedDate => _selectedDate ?? _today;

 /// get [_weeks]
 List<DateTime?> get rangeWeekDate => _weeks.isNotEmpty
  ? _weeks[_currentWeekIndex].days.where((ele) => ele != null).toList()
  : [];

 /// [Callback] for update widget event
 late Function(DateTime?) _widgetJumpToDate;

 /// Index of week display on the screen
 int _currentWeekIndex = 0;

 /// Store a list [DateTime] of weeks display on the screen
 final List<WeekItem> _weeks = [];

 /// [jumpToDate] show week contain [date] on the screen
 void jumpToDate(DateTime date) {
/// Find [_newCurrentWeekIndex] corresponding new [dateTime]
final _newCurrentWeekIndex = findCurrentWeekIndexByDate(date, _weeks);

/// If has matched, update [_currentWeekIndex], [_selectedDate]
/// and call [_widgetJumpToDate] for update widget
if (_newCurrentWeekIndex != -1) {
  _currentWeekIndex = _newCurrentWeekIndex;

  _selectedDate = date;

  /// Call [_widgetJumpToDate] for update Widget
  _widgetJumpToDate(_selectedDate);
    }
  }
   }

   class CalendarWeek extends StatefulWidget {
   /// Calendar start from [minDate]
  final DateTime minDate;

 /// Calendar end at [maxDate]
 final DateTime maxDate;

 /// Style of months
 final TextStyle monthStyle;

  /// Style of day of week
 final TextStyle dayOfWeekStyle;

  /// Style of weekends days
  final TextStyle weekendsStyle;

   /// Alignment of day day of week
     final FractionalOffset monthAlignment;

    /// Style of dates
     final TextStyle dateStyle;

   /// Specify a style for today
     final TextStyle todayDateStyle;

     /// Specify a background for today
       final Color todayBackgroundColor;

      /// Specify background for date after pressed
      final Color datePressedBackgroundColor;

     /// Specify a style for date after pressed
     final TextStyle datePressedStyle;

   /// Background for dates
  final Color dateBackgroundColor;

 /// [Callback] function for press event
  final void Function(DateTime) onDatePressed;

  /// [Callback] function for long press even
   final void Function(DateTime) onDateLongPressed;

  /// Background color of calendar
   final Color backgroundColor;

  /// List contain titles day of week
    final List<String> daysOfWeek;

    /// List contain title months
     final List<String> months;

    /// Condition show month
    final bool monthDisplay;

      /// List contain indexes of weekends from days titles list
     final List<int> weekendsIndexes;

     /// Margin day of week row
    final EdgeInsets marginDayOfWeek;

       /// Margin month row
       final EdgeInsets marginMonth;

        /// Shape of day
      final ShapeBorder dayShapeBorder;

    /// List of decorations
        final List<DecorationItem> decorations;

     /// Height of calendar
     final double height;

      /// Page controller
      final CalendarWeekController? controller;

      /// [Callback] changed week event
       final Function() onWeekChanged;

   CalendarWeek._(
  Key? key,
  this.maxDate,
  this.minDate,
  this.height,
  this.monthStyle,
  this.dayOfWeekStyle,
  this.monthAlignment,
  this.dateStyle,
  this.todayDateStyle,
  this.todayBackgroundColor,
  this.datePressedBackgroundColor,
  this.datePressedStyle,
  this.dateBackgroundColor,
  this.onDatePressed,
  this.onDateLongPressed,
  this.backgroundColor,
  this.daysOfWeek,
  this.months,
  this.monthDisplay,
  this.weekendsIndexes,
  this.weekendsStyle,
  this.marginMonth,
  this.marginDayOfWeek,
  this.dayShapeBorder,
  this.decorations,
  this.controller,
  this.onWeekChanged)
  : assert(daysOfWeek.length == 7),
    assert(months.length == 12),
    assert(minDate.isBefore(maxDate)),
    super(key: key);

      factory CalendarWeek(
      {Key? key,
      DateTime? maxDate,
      DateTime? minDate,
      double height = 100,
      TextStyle monthStyle =
          const TextStyle(color: Colors.blue, fontWeight: FontWeight.w600),
      TextStyle dayOfWeekStyle =
          const TextStyle(color: Colors.blue, fontWeight: FontWeight.w600),
      FractionalOffset monthAlignment = FractionalOffset.center,
      TextStyle dateStyle =
          const TextStyle(color: Colors.blue, fontWeight: FontWeight.w400),
      TextStyle todayDateStyle = const TextStyle(
          color: Colors.orange, fontWeight: FontWeight.w400),
      Color todayBackgroundColor = Colors.black12,
      Color pressedDateBackgroundColor = Colors.blue,
      TextStyle pressedDateStyle =
          const TextStyle(color: Colors.white, fontWeight: FontWeight.w400),
      Color dateBackgroundColor = Colors.transparent,
      Function(DateTime)? onDatePressed,
      Function(DateTime)? onDateLongPressed,
      Color backgroundColor = Colors.white,
      List<String> dayOfWeek = dayOfWeekDefault,
      List<String> month = monthDefaults,
      bool showMonth = true,
      List<int> weekendsIndexes = weekendsIndexesDefault,
      TextStyle weekendsStyle =
          const TextStyle(color: Colors.red, fontWeight: FontWeight.w600),
      EdgeInsets marginMonth = const EdgeInsets.symmetric(vertical: 4),
      EdgeInsets marginDayOfWeek = const EdgeInsets.symmetric(vertical: 4),
      CircleBorder dayShapeBorder = const CircleBorder(),
      List<DecorationItem> decorations = const [],
      CalendarWeekController? controller,
      Function()? onWeekChanged}) =>
   CalendarWeek._(
      key,
      maxDate ?? DateTime.now().add(Duration(days: 180)),
      minDate ?? DateTime.now().add(Duration(days: -180)),
      height,
      monthStyle,
      dayOfWeekStyle,
      monthAlignment,
      dateStyle,
      todayDateStyle,
      todayBackgroundColor,
      pressedDateBackgroundColor,
      pressedDateStyle,
      dateBackgroundColor,
      onDatePressed ?? (DateTime date) {},
      onDateLongPressed ?? (DateTime date) {},
      backgroundColor,
      dayOfWeek,
      month,
      showMonth,
      weekendsIndexes,
      weekendsStyle,
      marginMonth,
      marginDayOfWeek,
      dayShapeBorder,
      decorations,
      controller,
      onWeekChanged ?? () {});

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

       class _CalendarWeekState extends State<CalendarWeek> {
        /// [_streamController] for emit date press event
       final CacheStream<DateTime?> _cacheStream = CacheStream<DateTime?>();

        /// [_stream] for listen date change event
      Stream<DateTime?>? _stream;

     /// Page controller
    late PageController _pageController;

        CalendarWeekController _defaultCalendarController = CalendarWeekController();

     CalendarWeekController get controller =>
  widget.controller ?? _defaultCalendarController;

    void _jumToDateHandler(DateTime? dateTime) {
     _cacheStream.add(dateTime);
       _pageController.animateToPage(widget.controller!._currentWeekIndex,
    duration: Duration(milliseconds: 300), curve: Curves.ease);
       }

   void _setUp() {
   assert(controller.hasClient == false); // LINE of ERROR
  _stream ??= _cacheStream.stream!.asBroadcastStream();
   controller
   .._weeks.clear()
  .._weeks.addAll(separateWeeks(
      widget.minDate, widget.maxDate, widget.daysOfWeek, widget.months))

   /// [_currentWeekIndex] is index of week in [List] weeks contain today

    .._currentWeekIndex =
      findCurrentWeekIndexByDate(controller._today, controller._weeks)
    .._widgetJumpToDate = _jumToDateHandler
  .._hasClient = true;

  /// Init Page controller
       /// Set [initialPage] is page contain today
     _pageController = PageController(initialPage: controller._currentWeekIndex);
     }

   @override
   void initState() {
      super.initState();
    _setUp();
      }

       @override
      Widget build(BuildContext context) => _body();

   /// Body layout
      Widget _body() => Container(
  color: widget.backgroundColor,
  width: double.infinity,
  height: widget.height,
  child: PageView.builder(
    controller: _pageController,
    itemCount: controller._weeks.length,
    onPageChanged: (currentPage) {
      widget.controller!._currentWeekIndex = currentPage;
      widget.onWeekChanged();
    },
    itemBuilder: (_, i) => _week(controller._weeks[i]),
  ));

    /// Layout of week
     Widget _week(WeekItem weeks) => Column(
    mainAxisAlignment: MainAxisAlignment.start,
    children: <Widget>[
      // Month
      widget.monthDisplay ? _monthItem(weeks.month) : Container(),

      /// Day of week layout
      _dayOfWeek(weeks.dayOfWeek),

      /// Date layout
      _dates(weeks.days)
    ],
     );

     /// Day of week item layout
       Widget _monthItem(String title) => Align(
    alignment: widget.monthAlignment,
    child: Container(
        margin: widget.marginMonth,
        child: Text(
          title,
          style: widget.monthStyle,
          overflow: TextOverflow.ellipsis,
          textAlign: TextAlign.center,
        )),
  );

   /// Day of week layout
     Widget _dayOfWeek(List<String> dayOfWeek) => Container(
    margin: widget.marginDayOfWeek,
    child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: dayOfWeek.map(_dayOfWeekItem).toList()),
  );

    /// Day of week item layout
     Widget _dayOfWeekItem(String title) => Container(
  alignment: Alignment.center,
  child: FittedBox(
    fit: BoxFit.scaleDown,
    child: Container(
      width: 50,
      child: Text(
        title,
        style: widget.weekendsIndexes
                    .indexOf(widget.daysOfWeek.indexOf(title)) !=
                -1
            ? widget.weekendsStyle
            : widget.dayOfWeekStyle,
        overflow: TextOverflow.ellipsis,
        textAlign: TextAlign.center,
      ),
    ),
  ));

       /// Date layout
     Widget _dates(List<DateTime?> dates) => Row(
  mainAxisAlignment: MainAxisAlignment.spaceAround,
  children: dates.map(_dateItem).toList());

     /// Date item layout
       Widget _dateItem(DateTime? date) => DateItem(
  today: controller._today,
  date: date,
  dateStyle: compareDate(date, controller._today)
      ? widget.todayDateStyle
      : date != null && (date.weekday == 6 || date.weekday == 7)
          ? widget.weekendsStyle
          : widget.dateStyle,
  pressedDateStyle: widget.datePressedStyle,
  backgroundColor: widget.dateBackgroundColor,
  todayBackgroundColor: widget.todayBackgroundColor,
  pressedBackgroundColor: widget.datePressedBackgroundColor,
  decorationAlignment: () {
    /// If date is contain in decorations list, use decorations Alignment
    if (widget.decorations.isNotEmpty) {
      final List<DecorationItem> matchDate = widget.decorations
          .where((ele) => compareDate(ele.date, date))
          .toList();
      return matchDate.isNotEmpty
          ? matchDate[0].decorationAlignment
          : FractionalOffset.center;
    }
    return FractionalOffset.center;
  }(),
  dayShapeBorder: widget.dayShapeBorder,
  onDatePressed: (datePressed) {
    controller._selectedDate = datePressed;
    widget.onDatePressed(datePressed);
  },
  onDateLongPressed: (datePressed) {
    controller._selectedDate = datePressed;
    widget.onDateLongPressed(datePressed);
  },
  decoration: () {
    /// If date is contain in decorations list, use decorations Widget
    if (widget.decorations.isNotEmpty) {
      final List<DecorationItem> matchDate = widget.decorations
          .where((ele) => compareDate(ele.date, date))
          .toList();
      return matchDate.isNotEmpty ? matchDate[0].decoration : null;
    }
    return null;
  }(),
  cacheStream: _cacheStream);

    @override
     void dispose() {
       super.dispose();
        _cacheStream.close();
      }
    }

Exemple : Link github

and any setstate I use returns this error, the text returns the date selected when starting the app, but clicking on the desired date returns this error