Null check operator used on null value - flutter

Question

I need to grab a list of all messages in the database where the level is less than or equal to the user's current level. To do this I am attempting to use a nested streambuilder. First one pulls the user info, then I use the user level to make the second query. My problem is I get an error.
Null check operator used on null value
I do not understand this error. I checked firestore to see that there is data in the collection, and I also made sure to put the proper rules in place. I've tried several variations of this code and this is the only one so far that at least doesn't give me an error in the emulator. My emulator shows the appbar and the body is blank.
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import '../screens/welcome_screen.dart';
class MessagesScreen extends StatefulWidget {
static const String id = 'messages_screen';
#override
_MessagesScreenState createState() => _MessagesScreenState();
}
class _MessagesScreenState extends State<MessagesScreen> {
final _firestore = FirebaseFirestore.instance;
final _auth = FirebaseAuth.instance;
User loggedInUser;
int _userCurrentLevel;
#override
void initState() {
super.initState();
getCurrentUser();
}
void getCurrentUser() {
try {
final user = _auth.currentUser;
if (user != null) {
loggedInUser = user;
}
} catch (e) {
print(e);
}
}
getMessages(AsyncSnapshot<QuerySnapshot> snapshot2) {
return snapshot2.data.docs
.map((doc) => new ListTile(title: Text(doc['from']), subtitle: Text(doc['text'])))
.toList();
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
appBar: AppBar(
title: Text('Darker Slate'),
actions: <Widget>[
IconButton(
icon: const Icon(Icons.chat),
tooltip: 'Messages',
onPressed: () {},
),
IconButton(
icon: const Icon(Icons.exit_to_app),
tooltip: 'Log Out',
onPressed: () {
_auth.signOut();
Navigator.pushNamed(context, WelcomeScreen.id);
},
),
],
),
body: StreamBuilder<DocumentSnapshot>(
stream: _firestore.collection('users')
.doc(_auth.currentUser.uid)
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.red[900],
),
);
}
_userCurrentLevel = snapshot.data['userlevel'];
return StreamBuilder<QuerySnapshot>(
stream: _firestore.collection('messages')
.where('level', isLessThanOrEqualTo: _userCurrentLevel).snapshots(),
builder: (context, snapshot2) {
if (!snapshot2.hasData) {
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.red[900],
),
);
}
return Column(
children: [
ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: snapshot2.data.docs.length,
itemBuilder: (_, index) {
return new ListView(children: getMessages(snapshot2));
}),
],
);
}
);
}),
);
}
}