[web] WebView in production: Null check operator used on a null value

[kevinpthorne]

• I have read the Getting Started section
• I have already searched for the same problem

Environment

Technology	Version
Flutter version	3.19.3
Plugin version	6.0.0
Android version	n/a
iOS version	n/a
macOS version	(host) 14.4.1
Xcode version	n/a
Google Chrome version	124.0.6367.208 (arm64)

Device information: n/a

Description

Expected behavior: InAppWebView renders the iframe as it does in Flutter dev mode

Current behavior: No iframe rendered. Null check operator used on a null value with obfuscated stacktrace

Steps to reproduce

1. Make a widget with

  @override
  Widget build(BuildContext context) {
    return InAppWebView(
      initialData: InAppWebViewInitialData(data: "hello world"),
    );
  }

2. Run flutter run -d chrome -- verify it is functioning
3. Run flutter build web
4. Run some HTTP server in the build/web directory (e.g. python3 -m http.server --directory build/web 8002)
5. Visit the different http server, observe error

Images

Stacktrace/Logcat

Null check operator used on a null value
main.dart.js:28785     at Object.aTi (http:https://localhost:8002/main.dart.js:25467:19)
main.dart.js:28785     at Object.aS7 (http:https://localhost:8002/main.dart.js:25461:26)
main.dart.js:28785     at TG.I (http:https://localhost:8002/main.dart.js:49797:10)
main.dart.js:28785     at Si.bi (http:https://localhost:8002/main.dart.js:75771:18)
main.dart.js:28785     at Si.kN (http:https://localhost:8002/main.dart.js:75747:9)
main.dart.js:28785     at Si.BR (http:https://localhost:8002/main.dart.js:75699:10)
main.dart.js:28785     at Si.YS (http:https://localhost:8002/main.dart.js:75700:18)
main.dart.js:28785     at Si.Ey (http:https://localhost:8002/main.dart.js:75745:11)
main.dart.js:28785     at Si.fc (http:https://localhost:8002/main.dart.js:75744:6)
main.dart.js:28785     at rd.vv (http:https://localhost:8002/main.dart.js:75612:3)

[github-actions]

👋 @kevinpthorne

NOTE: This comment is auto-generated.

Are you sure you have already searched for the same problem?

Some people open new issues but they didn't search for something similar or for the same issue. Please, search for it using the GitHub issue search box or on the official inappwebview.dev website, or, also, using Google, StackOverflow, etc. before posting a new one. You may already find an answer to your problem!

If this is really a new issue, then thank you for raising it. I will investigate it and get back to you as soon as possible. Please, make sure you have given me as much context as possible! Also, if you didn't already, post a code example that can replicate this issue.

In the meantime, you can already search for some possible solutions online! Because this plugin uses native WebView, you can search online for the same issue adding android WebView [MY ERROR HERE] or ios WKWebView [MY ERROR HERE] keywords.

Following these steps can save you, me, and other people a lot of time, thanks!

[kevinpthorne]

Any tips on decoding this stacktrace? That's where I am stuck currently

[kevinpthorne]

Looks like this was a case of my browser or dart compiler caching things -- now I'm just working around flutter/flutter#86833' since I am serving HTML and CSS assets...on the web inappwebview (I know its weird)

Tips for posterity:

• If you're using something like python3 -m http.server to serve the compiled web folder, be sure to cycle ports as you troubleshoot
• flutter clean is always a good nuke option
• Don't use the workaround here Inconsistent Asset Image path across Mobile and Web platforms flutter/flutter#86833 (comment). For some reason this messed with everything.
• Ensure the flutter source map json is getting generated using debug flags on flutter build (i.e. [web] exception stack trace with javascript files instead of dart  flutter/flutter#101888 (comment))