# Gtk: gtk\_notebook\_get\_tab\_label: assertion 'list != NULL' failed

**URL:** <https://racket.discourse.group/t/gtk-gtk-notebook-get-tab-label-assertion-list-null-failed/2373>\
**Category:** General\
**Created:** [October 7, 2023, 4:27pm UTC](https://racket.discourse.group/t/gtk-gtk-notebook-get-tab-label-assertion-list-null-failed/2373 "2023-10-07T16:27:51Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Laurent.O](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/laurent.o/32/18_2.png) [@Laurent.O](https://racket.discourse.group/u/Laurent.O)\
**Post date:** [October 7, 2023, 4:27pm UTC](https://racket.discourse.group/t/gtk-gtk-notebook-get-tab-label-assertion-list-null-failed/2373/1 "2023-10-07T16:27:51Z")

</div>

When testing `quickscript-test`, I have some GTK errors that I didn't use to have:

```scheme
Gtk: gtk_notebook_get_tab_label: assertion 'list != NULL' failed

```

This appears to be a non-Racket-specific bug, e.g.  
[linux mint](https://github.com/linuxmint/linuxmint/issues/485). There seems to be a patch which has been applied inconsistently.

This make the tests fail for no particularly good reason, in particular since everything appears to be working fine (as far as I can tell).

Is there a way to turn these notices off and let the tests continue as normal?

---

<div class="post-metadata">

**Author:** ![Laurent.O](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/laurent.o/32/18_2.png) [@Laurent.O](https://racket.discourse.group/u/Laurent.O)\
**Post date:** [October 8, 2023, 5:03pm UTC](https://racket.discourse.group/t/gtk-gtk-notebook-get-tab-label-assertion-list-null-failed/2373/2 "2023-10-08T17:03:35Z")

</div>

It appears to be a bug on DrRacket's side (or deeper), when closing a tab. Filed an issue here:

> <https://github.com/racket/drracket/issues/645>
>
> To reproduce:
> 1. Open DrRacket from the command line to see the error port outp…uts in the console.
> 2. Open a new tab.
> 3. Close the tab (either from the menu or with a keyboard shortcut)
> 
> The following error message is displayed in the console:
> \`\`\`
> Gtk: gtk\_notebook\_get\_tab\_label: assertion 'list != NULL' failed
> \`\`\`
> 
> While the tab does close and the message seems innocuous, it get displayed on the error port which breaks some tests (such as quickscript-test).
> 
> Related: https://racket.discourse.group/t/gtk-gtk-notebook-get-tab-label-assertion-list-null-failed/2373