Printing fails on Web, with the error "TypeError: null: type 'Null' is not a subtype of type 'JSObject'"

[nirmal-kc]

Describe the bug Printing fails on Web, with the error "TypeError: null: type 'Null' is not a subtype of type 'JSObject'"

To Reproduce Download the latest code from GitHub repo. And run it on the latest version of Flutter

Expected behavior The print window must open.

Screenshots Flutter Doctor

^[[A[✓] Flutter (Channel stable, 3.24.3, on macOS 15.0 24A335 darwin-arm64, locale en-IN)
[!] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    ✗ cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/to/macos-android-setup for more details.
⣷[✓] Xcode - develop for iOS and macOS (Xcode 16.0)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2024.1)
[✓] VS Code (version 1.93.1)
[✓] Connected device (4 available)
[✓] Network resources

Desktop (please complete the following information):

• Browser

[Sarkheelmughal]

same issue with me

[FadyShehataa]

same issue with me. anyone get solution ?

[blakix]

same issue

[nirmal-kc]

The issue is thrown from printing_web.dart line no 196.

final isSafari = web.window['safari'].isUndefinedOrNull &&
        !userAgent.contains(RegExp(r'Version/14\.1\.'));

Replacing it with a simple try/catch block fixed the issue.

    bool isSafari;
    try {
      isSafari = web.window['safari'].isUndefinedOrNull &&
          !userAgent.contains(RegExp(r'Version/14\.1\.'));
    } catch (e) {
      isSafari = false;
    }

Can any of the contributors push this code to the repo? Thanks in advance.

[blakix]

Thanks nirmal-kc for your answer. It partially solved the problem for me. It only generates the PDF but the print window does not appear.

[nirmal-kc]

@blakix : My bad, I checked it in a hurry. Please replace the code for isChrome and isSafari as shown below. Let me know incase of any concerns.

    final userAgent = web.window.navigator.userAgent;
    //UserAgent can contain both Chrome and Safari for Chrome browser.
    //Ex:  Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.79 Safari/537.4
    final isChrome = userAgent.contains('Chrome');
    //UserAgent contains only Safari for Safari browser.
    //Ex: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/536.26.14 (KHTML, like Gecko) Version/6.0.1 Safari/536.26.14
    final isSafari =
        userAgent.contains('Safari') && !userAgent.contains('Chrome');

[Sarkheelmughal]

@nirmal-kc thanks now its working fine

[blakix]

Thanks nirmal-kc for all. It is perfect now. Thank you👌 find file here: C:\Users\user\AppData\Local\Pub\Cache\hosted\pub.dev\printing-5.13.3\lib\printing_web.dart

[DavBfr]

Pushed to master.

[BrenoAugustoComandolli]

Hi, I would like to know in which version this fix will come out.