Flutter: The method '/' was called on null. Receiver: null Tried calling: /(1080.0) - flutter

Question

I'm getting this error since I've used Media Query for setting up Responsive UI. Below is the error that I'm getting in the terminal.
I don't know which method calling is returning null according to Dart. Because I'm navigating to new Screen via Raised Button and it is showing this error on Constructor of Widget/Class that I called on onPressed of the button
Here is the code of my class from where I'm navigating to new Screen of Doctor's Login:
import 'dart:io';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:medkit/animations/fadeAnimation.dart';
import 'package:medkit/animations/bottomAnimation.dart';
import 'package:medkit/doctor/doctorLogin.dart';
import 'package:medkit/doctor/doctorPanel.dart';
import 'aboutUs.dart';
class UserType extends StatelessWidget {
#override
Widget build(BuildContext context) {
double width = MediaQuery.of(context).size.width;
double height = MediaQuery.of(context).size.height;
Future<bool> _onWillPop() async {
return (await showDialog(
context: context,
builder: (context) => new AlertDialog(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(12)
),
title: new Text(
"Exit Application",
style: TextStyle(fontWeight: FontWeight.bold),
),
content: new Text("Are You Sure?"),
actions: <Widget>[
// usually buttons at the bottom of the dialog
FlatButton(
shape: StadiumBorder(),
color: Colors.white,
child: new Text(
"Close",
style: TextStyle(color: Colors.blue),
),
onPressed: () {
Navigator.of(context).pop();
},
),
FlatButton(
shape: StadiumBorder(),
color: Colors.white,
child: new Text(
"Yes",
style: TextStyle(color: Colors.red),
),
onPressed: () {
exit(0);
},
),
],
),
)) ??
false;
}
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
body: SafeArea(
child: Padding(
padding: EdgeInsets.symmetric(horizontal: width * 0.04),
child: Column(
children: <Widget>[
SizedBox(
height: height * 0.08,
),
FadeAnimation(
0.3,
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(
'Category',
style: TextStyle(color: Colors.black, fontSize: 30),
),
GestureDetector(
onTap: () => _exitAlert(context),
child: Icon(
Icons.exit_to_app,
size: height * 0.04,
),
)
],
),
),
SizedBox(height: height * 0.09),
Column(
children: <Widget>[
FadeAnimation(
0.4,
CircleAvatar(
backgroundColor: Colors.black.withOpacity(0.2),
radius: height * 0.075,
child: Image(image: AssetImage("assets/doctor.png")),
),
),
WidgetAnimator(patDocBtn('Doctor', context)),
SizedBox(
height: height * 0.1,
),
FadeAnimation(
0.4,
CircleAvatar(
backgroundColor: Colors.black.withOpacity(0.2),
radius: height * 0.075,
child: Image(image: AssetImage("assets/patient.png")),
),
),
WidgetAnimator(patDocBtn('Patient', context)),
SizedBox(height: height * 0.13,),
GestureDetector(
onTap: () => Navigator.push(context, new MaterialPageRoute(builder: (context) => AboutUs())),
child: Column(
children: <Widget>[
Text('Version', style: TextStyle(fontWeight: FontWeight.bold),),
Text('V 0.1', style: TextStyle(fontSize: 12),)
],
),
),
SizedBox(height: 5,)
],
)
],
),
),
),
),
);
}
Widget patDocBtn(String categoryText, context) {
return Container(
width: MediaQuery.of(context).size.width * 0.5,
child: RaisedButton(
onPressed: () {
if (categoryText == 'Doctor') {
Navigator.pushNamed(context, 'DoctorLogin');
} else {
Navigator.pushNamed(context, 'PatientLogin');
}
},
color: Colors.white,
child: Text("I am " + categoryText),
shape: StadiumBorder(),
),
);
}
_exitAlert(context) {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(12)
),
title: new Text(
"Exit Application",
style: TextStyle(fontWeight: FontWeight.bold),
),
content: new Text("Are You Sure?"),
actions: <Widget>[
// usually buttons at the bottom of the dialog
FlatButton(
color: Colors.white,
child: new Text(
"Close",
style: TextStyle(color: Colors.blue),
),
onPressed: () {
Navigator.of(context).pop();
},
),
FlatButton(
color: Colors.white,
child: new Text(
"Yes",
style: TextStyle(color: Colors.red),
),
onPressed: () {
exit(0);
},
),
],
);
},
);
}
}
And here is Doctor's Login class code
import 'dart:math';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:medkit/animations/fadeAnimation.dart';
import 'package:medkit/animations/bottomAnimation.dart';
import 'package:medkit/doctor/doctorPanel.dart';
import 'package:medkit/otherWidgetsAndScreen/backBtn.dart';
import 'package:medkit/otherWidgetsAndScreen/imageAvatar.dart';
import 'package:toast/toast.dart';
class DoctorLogin extends StatefulWidget {
#override
_DoctorLoginState createState() => _DoctorLoginState();
}
class _DoctorLoginState extends State<DoctorLogin> {
final FirebaseAuth _firebaseAuth = FirebaseAuth.instance;
final GoogleSignIn _googleSignIn = new GoogleSignIn();
Future<FirebaseUser> _signIn(BuildContext context) async {
final GoogleSignInAccount googleUser = await _googleSignIn.signIn();
final GoogleSignInAuthentication googleAuth =
await googleUser.authentication;
final AuthCredential credential = GoogleAuthProvider.getCredential(
idToken: googleAuth.idToken, accessToken: googleAuth.accessToken);
FirebaseUser userDetails =
await _firebaseAuth.signInWithCredential(credential);
ProviderDoctorDetails providerInfo =
new ProviderDoctorDetails(userDetails.providerId);
List<ProviderDoctorDetails> providerData =
new List<ProviderDoctorDetails>();
providerData.add(providerInfo);
DoctorDetails details = new DoctorDetails(
userDetails.providerId,
userDetails.displayName,
userDetails.photoUrl,
userDetails.email,
providerData,
);
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => DoctorPanel(
detailsUser: details,
)));
return userDetails;
}
#override
Widget build(BuildContext context) {
final nameTextFieldController = TextEditingController();
final nameTextField = TextField(
keyboardType: TextInputType.text,
autofocus: false,
maxLength: 30,
textInputAction: TextInputAction.next,
onSubmitted: (_) => FocusScope.of(context).nextFocus(),
controller: nameTextFieldController,
decoration: InputDecoration(
fillColor: Colors.black.withOpacity(0.07),
filled: true,
labelText: 'Enter Name',
prefixIcon: Icon(Icons.person),
border: OutlineInputBorder(
borderRadius: const BorderRadius.all(const Radius.circular(20)))),
);
final phNumberTextController = TextEditingController();
final phoneTextField = TextField(
keyboardType: TextInputType.phone,
autofocus: false,
maxLength: 11,
controller: phNumberTextController,
textInputAction: TextInputAction.next,
onSubmitted: (_) => FocusScope.of(context).nextFocus(),
decoration: InputDecoration(
filled: true,
fillColor: Colors.black.withOpacity(0.07),
labelText: 'Enter Number',
prefixIcon: Icon(Icons.phone),
border: new OutlineInputBorder(
borderRadius: const BorderRadius.all(const Radius.circular(20)),
),
),
);
final cnicTextController = TextEditingController();
final cnicTextField = TextFormField(
keyboardType: TextInputType.number,
autofocus: false,
maxLength: 13,
controller: cnicTextController,
decoration: InputDecoration(
filled: true,
fillColor: Colors.black.withOpacity(0.07),
labelText: 'Enter CNIC',
prefixIcon: Icon(Icons.card_membership),
border: OutlineInputBorder(borderRadius: BorderRadius.circular(20))),
);
final double width = MediaQuery.of(context).size.width;
final double height = MediaQuery.of(context).size.height;
return GestureDetector(
onTap: () {
FocusScopeNode currentFocus = FocusScope.of(context);
if (!currentFocus.hasPrimaryFocus) {
currentFocus.unfocus();
}
},
child: Scaffold(
resizeToAvoidBottomPadding: false,
body: SafeArea(
child: Container(
width: width,
height: height,
child: Stack(
children: <Widget>[
ImageAvatar(
assetImage: 'assets/bigDoc.png',
),
Container(
width: width,
height: height,
margin: EdgeInsets.fromLTRB(width * 0.03, 0, width * 0.03, 0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
BackBtn(),
SizedBox(height: height * 0.05,),
Text(
"\t\tLogin",
style: GoogleFonts.abel(
fontSize: ScreenUtil.instance.setSp(35),
fontWeight: FontWeight.bold),
),
SizedBox(
height: height * 0.05,
),
WidgetAnimator(nameTextField),
WidgetAnimator(phoneTextField),
WidgetAnimator(cnicTextField),
SizedBox(height: height * 0.01,),
FadeAnimation(
1.5,
SizedBox(
width: width,
height: height * 0.07,
child: RaisedButton(
color: Colors.white,
shape: StadiumBorder(),
onPressed: () {
if (nameTextFieldController.text != "" ||
phNumberTextController.text != "" ||
cnicTextController.text != "") {
Firestore.instance
.collection('doctorInfo')
.document(nameTextFieldController.text)
.setData({
'cnic': cnicTextController.text,
'phoneNumber': phNumberTextController.text,
});
_signIn(context)
.then((FirebaseUser user) =>
print('Gmail Logged In'))
.catchError((e) => print(e));
nameTextFieldController.clear();
cnicTextController.clear();
phNumberTextController.clear();
} else {
Toast.show('Fields Cannot be Empty!', context,
backgroundColor: Colors.red,
gravity: Toast.CENTER,
duration: Toast.LENGTH_SHORT);
}
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Image(
image: AssetImage('assets/google.png'),
height: ScreenUtil.instance.setHeight(35),
),
SizedBox(width: ScreenUtil.instance.setWidth(15)),
Text(
'Login',
style: TextStyle(
letterSpacing: 2,
fontWeight: FontWeight.bold,
fontSize: ScreenUtil.instance.setSp(18)),
)
],
),
),
),
),
SizedBox(height: height * 0.02,),
FadeAnimation(
2,
Text(
'You Will be asked Question regarding your Qualifications!', textAlign: TextAlign.center,
style: TextStyle(color: Colors.black.withOpacity(0.5),),
),
),
],
),
),
],
),
),
)),
);
}
}
class DoctorDetails {
final String providerDetails;
final String userName;
final String photoUrl;
final String userEmail;
final List<ProviderDoctorDetails> providerData;
DoctorDetails(this.providerDetails, this.userName, this.photoUrl,
this.userEmail, this.providerData);
}
class ProviderDoctorDetails {
ProviderDoctorDetails(this.providerDetails);
final String providerDetails;
}

Answer 1

Solution
I was using Media Query along with a 3rd party dependency at same time. I just removed that Dependency and its use in my code and it solved
Conclusion
Probably you can't use Media Query along with third party dependency at same time for making your app responsive

Answer 2

Your pushNamed route, the route name starts with '/'? Did you declare it as '/NAMEOFTHEROUTE'?
If yes please use your pushNamed as'/NAMEOFTHEROUTE'.