Why does it throw an Unhandled Exception here? - flutter

Question

I'm trying to persist my calendar data with hive but when I start the program, it throws this:
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: type 'Null' is not a subtype of type 'bool' in type cast
This is my model class:
#HiveType(typeId: 1)
class Event extends HiveObject {
#HiveField(0)
late String title;
#HiveField(1)
late DateTime eventDateTime;
#HiveField(2)
bool wholeDayEvent;
Event({
required this.title,
required this.eventDateTime,
required this.wholeDayEvent,
});
#override
String toString() => title;
}
And here's the build method of my displaying widget:
Expanded(
child: ValueListenableBuilder<Box<Event>>(
valueListenable: Boxes.getEvents().listenable(),
builder: (context, box, _) {
final events = box.values.toList().cast<Event>();
return ListView.builder(
itemCount: events.length,
itemBuilder: (context, index) {
return Container(
margin: const EdgeInsets.symmetric(
horizontal: 12.0,
vertical: 4.0,
),
decoration: BoxDecoration(
border: Border.all(),
borderRadius: BorderRadius.circular(12.0),
),
child: ListTile(
onTap: () => print('${box.values}'),
title: Text('${box.values}'),
),
);
},
);
},
),
),

Answer 1

I can assume that you changed some fields in your Event object, while your Hive database is not empty, so the previously stored objects do not have those new fields so their values are null, which throws the error.
You can fix this by simply clearing your Hive box before using it, so it deletes the previous data objects and work with the new one, in your main():
await Hive.openBox<Event>("yourBoxName"); // opens the box
await Hive.box<Event>("yourBoxName").clear(); // clear the box
Now you will have an empty box, and your code will work fine again.
you should just clear it one time to remove previous data, after that you could remove the clear() line and work normally.