This gist is a small Flutter app that reproduces a (re)layout error. Use this as your main.dart in a hello_world app.

main.dart

import 'dart:async';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: RelayoutBoundariesCrash(),
    );
  }
}

class RelayoutBoundariesCrash extends StatefulWidget {
  RelayoutBoundariesCrash({Key key}) : super(key: key);

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

class _RelayoutBoundariesCrashState extends State<RelayoutBoundariesCrash> {
  bool _visible;

  void _toggleVisibility() {
    setState(() {
      _visible = !_visible;
    });
  }

  _RelayoutBoundariesCrashState() {
    _visible = true;
    // Toggle visibility automatically, doesn't matter how you toggle this
    Timer(Duration(milliseconds: 1000), () {
      _toggleVisibility();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SizedBox( // Must be a SizedBox (?)
          // *both* width AND height need to end up as 0x0
          width: !_visible ? 0 : null,
          height: !_visible ? 0 : null,
          child: LayoutBuilder(
              builder: (BuildContext context, BoxConstraints constraints) {
                final double width = !_visible ? 0 : 100;
                final double height = !_visible ? 0 : 100;

                return Column( // Also fails with Row
                  children: <Widget>[
                      SizedBox(
                        width: width,
                        height: height,
                        child: Text("Anything"),
                      ),
                      SizedBox( // This SizedBox throws the assert
                        width: width,
                        height: height,
                        child: Text("Something else"),
                      ),
                    ],
                );
              }),
      ),
//      floatingActionButton: FloatingActionButton( // Toggle manually
//        onPressed: _toggleVisibility,
//        tooltip: 'Crash',
//        child: _visible ? Icon(Icons.visibility_off) : Icon(Icons.visibility),
//      ),
    );
  }
}