Flutter program crashing

I’m new to Flutter/Dart and am trying to write a login UI. When I attempt to run the program, the debugger stops at this, errors_patch.dart which I assume is built-in:

@pragma("vm:external-name", "AssertionError_throwNew")
  external static _doThrowNew(
      int assertionStart, int assertionEnd, Object? message);
  @pragma("vm:external-name", "AssertionError_throwNewSource")
  external static _doThrowNewSource(
      String failedAssertion, int line, int column, Object? message);

How do I proceed? I’ve not modified any settings files or something. Android Studio and Flutter/Dart are up-to-date, and I’ve previously built this project. Something here is breaking but the editor (VS Code) doesn’t indicate any errors or warnings.

Here is all my source code:

• lib/main.dart

  import 'package:flutter/material.dart';
  import 'config.dart';
  import 'ui/setup/login_page.dart';
  
  void main() {
    runApp(const MyApp());
  }
  
  class MyApp extends StatelessWidget {
    const MyApp({super.key});
  
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'WiCon',
        theme: wiconTheme,
        home: const MainPage(),
      );
    }
  }
  
  class MainPage extends StatelessWidget {
    const MainPage({super.key});
  
    @override
    Widget build(BuildContext context) {
      return loginPage;
    }
  }
  

• lib/ui/setup/login_page.dart

      import 'package:flutter/material.dart';
  
  var loginPage = Scaffold(
  
    appBar: AppBar(
      title: Row(
        children: const [
          Padding(
            padding: EdgeInsets.all(8.0),
            child: Icon(Icons.wifi),
          ),
          Padding(
            padding: EdgeInsets.all(8.0),
            child: Text("WiCon"),
          ),
        ],
      ),
    ),
  
    body: Row(
      children: [
        // Left side
        // Define the welcome message
        Column(
          children: const [
            Padding(
              padding: EdgeInsets.all(8.0),
              child: Text("Welcome to WiCon"),
            ),
            Padding(
              padding: EdgeInsets.all(8.0),
              child: Text("Please login to continue"),
            ),
          ],
        ),
  
        // Right side
        // Define the form, buttons, and status info
        Column(
          children: [
            Form(
              child: Column(
                children: [
                  TextFormField(
                    decoration: const InputDecoration(labelText: "Register Number"),
                  ),
                  TextFormField(
                    decoration: const InputDecoration(
                      labelText: "Password",
                    ),
                    obscureText: true,
                  ),
                ],
              ),
            ),
          ],
        )
      ],
    ),
  );
  

• lib/config.dart

  import 'package:flutter/material.dart';
  
  final wiconTheme = ThemeData(
  useMaterial3: true,
  primarySwatch: Colors.blue,
  );
  

>Solution :

This happens due to the usage of Columns in Row. You have use Expanded or Flexible, or SizedBox with fixed with to solve this.
I used Flexible to solve this issue as following.

var loginPage = Scaffold(
      appBar: AppBar(
        title: Row(
          children: const [
            Padding(
              padding: EdgeInsets.all(8.0),
              child: Icon(Icons.wifi),
            ),
            Padding(
              padding: EdgeInsets.all(8.0),
              child: Text("WiCon"),
            ),
          ],
        ),
      ),

      body: Row(
        children: [
          // Left side
          // Define the welcome message
          Flexible(
            child: Column(
              children: const [
                Padding(
                  padding: EdgeInsets.all(8.0),
                  child: Text("Welcome to WiCon"),
                ),
                Padding(
                  padding: EdgeInsets.all(8.0),
                  child: Text("Please login to continue"),
                ),
              ],
            ),
          ),

          // Right side
          // Define the form, buttons, and status info
          Flexible(
            child: Column(
              children: [
                Form(
                  child: Column(
                    children: [
                      TextFormField(
                        decoration: const InputDecoration(labelText: "Register Number"),
                      ),
                      TextFormField(
                        decoration: const InputDecoration(
                          labelText: "Password",
                        ),
                        obscureText: true,
                      ),
                    ],
                  ),
                ),
              ],
            ),
          )
        ],
      ),
    )

Also you can use flex to decide the size of Row‘s children.

I hope this helps.