Implicit animation loads in dev mode but fails in build.

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  double height = 100;

  void changesize() {
    setState(() {
      height == 100 ? height = 200 : height = 100;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Stack(
          children: <Widget>[
            AnimatedContainer(
              duration: Duration(seconds: 1),
              color: Colors.red,
              width: 300,
              height: height,
            )
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: changesize,
        tooltip: 'Increment',
        child: Icon(Icons.format_size_sharp),
      ),
    );
  }
}