Class and Object

hello coach , aku nulis code seperti ini

class Manusia{
String nama;
int umur ;
//constructor = > NamaClass(isiAtribut)
Manusia({this.nama, this.umur});
}
void main (){

var m1 = Manusia(nama :’andi’, umur :17);
print (m1.nama);
print (m1.umur);
}

namun ketika di run :

Error compiling to JavaScript:
Info: Compiling with sound null safety
lib/main.dart:6:16:
Error: The parameter ‘nama’ can’t have a value of ‘null’ because of its type ‘String’, but the implicit default value is ‘null’.
Manusia({this.nama, this.umur});
^^^^
lib/main.dart:6:27:
Error: The parameter ‘umur’ can’t have a value of ‘null’ because of its type ‘int’, but the implicit default value is ‘null’.
Manusia({this.nama, this.umur});
^^^^
Error: Compilation failed.

padahal di video coach ga ada error. 😐