Empty VSCode plugin webview editor windows

[bvenreply]

Bug Description:

VSCode plugin webview editor windows are not displayed correctly. See this screenshot:

Left is a hello world vsce webview as loaded by current master. Right is the same webview after reverting this commit 72421be

Upon opening the webview this error is logged:

2024-01-10T17:16:06.195Z root ERROR [hosted-plugin: 586850] Promise rejection not handled in one second: Error: Unknown Webview: 0917c540-d516-4f59-ace9-bb9fff13c70c , reason: Error: Unknown Webview: 0917c540-d516-4f59-ace9-bb9fff13c70c
With stack trace: Error: Unknown Webview: 0917c540-d516-4f59-ace9-bb9fff13c70c
    at WebviewsMainImpl.getWebview (http://localhost:3000/packages_plugin-ext_lib_hosted_browser_hosted-plugin_js.js:13987:19)
    at async WebviewsMainImpl.$setHtml (http://localhost:3000/packages_plugin-ext_lib_hosted_browser_hosted-plugin_js.js:13917:25)
    at async RpcProtocol.handleRequest (http://localhost:3000/bundle.js:147209:28)

Steps to Reproduce:

This can be reproduced on the Theia browser example. You will also need a sample VSCode extension, I pushed the source code for the one used above here. You can build it with npm install && npx --yes --package @vscode/vsce vsce package --skip-license --allow-missing-repository.

• Open Theia
• Install the sample vsce
• Open the command palette and select Open HelloWorld webview
• Observe the empty window and error logged in the backend

Additional Information

• Operating System: 6.1.0-17-amd64 GNU/Linux
• Theia Version: master (6a7bd87)
• Browser: Chromium version 119

[dhuebner]

I'm facing the same issue and can confirm that reverting 72421be solves the problem.

[JonasHelming]

@jfaltermeier Could you take a look, please?

[jfaltermeier]

Sure, the widget seems to be in the pending map still and this.widgetManager.getWidgets does not include pending widgets. I'll look for a fix.

[jfaltermeier]

@bvenreply @dhuebner If you have the time, could you please check whether #13265 fixes the issue for you?

[bvenreply]

I tested the new code, the issue is fixed on my end. Thank you @jfaltermeier.

[bvenreply]

Actually @jfaltermeier, when I wrote the above I'd tested only the "hello world" extension I'd provided as a minimum example, testing the extension that initially prompted the bug report I still se some problems.

The webview editor window is still empty in that case, and in the console I see errors when trying to fetch subresources:

There is no more Unknown Webview error logged in the backend, in fact there is no error at all except for the 404s in the browser.

Let me know if I can provide any more details. BTW The extension I'm using is proprietary and that is why I have avoided sharing it. If needed I can ask permission to share it, but probably any extension that loads subresources in an editor webview will have the same issue.

I'm also interested in any similar feedback from @dhuebner.

[jfaltermeier]

Thanks, I'll have another look. I was able to create a reproducer.

[dhuebner]

@bvenreply
Sure! I can test the new state with my extension when @jfaltermeier is finished his PR.

[jfaltermeier]

I've updated the PR. The initial reproducer and the vs code coding cat example (https://github.com/microsoft/vscode-extension-samples/blob/main/webview-sample/README.md) are both working + the initial reproducer of 72421be

If there are still issues, I will open a 2nd PR to revert 72421be for now, and work on the further issues in parallel.

[bvenreply]

I checked again and I see no more issues on my end. Thank you @jfaltermeier.