Exception if you change month and go to another year

[m-gug]

If you change the month and switch to another year, an exception is thrown. So to be precise, when you change from December to January and vice versa, an exception occurs. The error occurs when navigating using the swipe gesture or using the arrow buttons.

Tested with Version: 0.3.17+37

A workaround is this: onMonthChanged: (_) {}

Exception:

FlutterErrorDetails (══╡ EXCEPTION CAUGHT BY GESTURE ╞════════════════════════════════
The following _TypeError was thrown while handling a gesture:
Null check operator used on a null value

When the exception was thrown, this was the stack:
#0      _CalendarState._launchDateSelectionCallback (package:flutter_neat_and_clean_calendar/flutter_neat_and_clean_calendar.dart:1051:28)
#1      _CalendarState.nextMonth (package:flutter_neat_and_clean_calendar/flutter_neat_and_clean_calendar.dart:834:7)
#2      _CalendarState._onSwipeLeft (package:flutter_neat_and_clean_calendar/flutter_neat_and_clean_calendar.dart:972:7)
#3      _SimpleGestureDetectorState._onHorizontalDragUpdate (package:flutter_neat_and_clean_calendar/simple_gesture_detector.dart:98:32)
#4      DragGestureRecognizer._checkUpdate.<anonymous closure> (package:flutter/src/gestures/monodrag.dart:581:55)
#5      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:315:24)
#6      DragGestureRecognizer._checkUpdate (package:flutter/src/gestures/monodrag.dart:581:7)
#7      DragGestureRecognizer.handleEvent (package:flutter/src/gestures/monodrag.dart:422:9)
#8      PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:98:12)
#9      PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:143:9)
#10     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:633:13)
#11     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:141:18)
#12     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:127:7)
#13     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:495:19)
#14     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:475:22)
#15     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:430:11)
#16     GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:420:7)
#17     GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:383:5)
#18     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:330:7)
#19     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:299:9)
#23     _invoke1 (dart:ui/hooks.dart:330:10)
#24     PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:429:7)
#25     _dispatchPointerDataPacket (dart:ui/hooks.dart:262:31)
(elided 3 frames from dart:async)

Handler: "onUpdate"
Recognizer:
  HorizontalDragGestureRecognizer#7bfbc
═════════════════════════════════════════════════════════════════
)

[rwbr]

Sorry for that. I can reproduce the faulty behavior. I will fix this as soon as possible.

[m-gug]

No problem, thank you!

[rwbr]

Fixed with v0.3.18+40