Webviews don't render as of version 1.12.0

[Jarthianur]

Bug Description:

Webviews don't show any content, just a blank editor panel. This happens for example when opening a markdown document using builtin extension (1.49.3+). Said behavior started with latest release 1.12.0. No errors are emitted in console or theia.

Steps to Reproduce:

1. build a basic theia application as docker image
2. run container and access via browser
3. open any markdown document
4. find a blank editor panel instead of the files content

Additional Information

I know of the breaking change regarding webviews and their unique origin. All resources are received properly (no DNS or proxy issues). It's just that the webview seems to "do nothing". I've tried with Firefox, Chrome, HTTPS and HTTP, with and without proxy, on localhost and remotely, and also different versions of builtin extensions. The behavior is always the same.

I would like to add some screenshots, but GH even tells me "something went wrong" for 5MiB jpegs.

These are the requested resources involved at opening the file.

http://1e6d5e59-0a98-44c9-b130-03dc61356e26.webview.localhost:3000/webview/main.js
http://1e6d5e59-0a98-44c9-b130-03dc61356e26.webview.localhost:3000/webview/host.js
http://1e6d5e59-0a98-44c9-b130-03dc61356e26.webview.localhost:3000/webview/service-worker.js
http://1e6d5e59-0a98-44c9-b130-03dc61356e26.webview.localhost:3000/webview/fake.html?id=1e6d5e59-0a98-44c9-b130-03dc61356e26

• Operating System: Linux
• Theia Version: 1.12.0

[vince-fugnitto]

@Jarthianur can you confirm which version of vscode-builtin-markdown-language-features you are using?
Newer versions such as 1.49.3 do not work due to #8752:

Backend Log:

root ERROR [hosted-plugin: 20568] With stack trace: TypeError: i.Uri.joinPath is not a function
    at t.MarkdownContentProvider.extensionResourcePath (/home/evinfug/workspaces/theia-work/plugins/vscode-builtin-markdown-language-features/extension/dist/extension.js:1:64434)
    at t.MarkdownContentProvider.provideTextDocumentContent (/home/evinfug/workspaces/theia-work/plugins/vscode-builtin-markdown-language-features/extension/dist/extension.js:1:63727)
    at processTicksAndRejections (internal/process/task_queues.js:94:5)
    at async g.updatePreview (/home/evinfug/workspaces/theia-work/plugins/vscode-builtin-markdown-language-features/extension/dist/extension.js:1:74049)
    ```

[Jarthianur]

@vince-fugnitto Yes, I can confirm that. I'll try out an earlier version.
Interestingly with the previous theia release 1.11, even version 1.51.1 of all builtins ran fine.

[vince-fugnitto]

@vince-fugnitto Yes, I can confirm that. I'll try out an earlier version.

You can try with the version we use as part of the examples:

• theia/package.json

  Line 118 in 57f0695

  "vscode-builtin-markdown-language-features": "https://open-vsx.org/api/vscode/markdown-language-features/1.39.2/file/vscode.markdown-language-features-1.39.2.vsix",

Interestingly with the previous theia release 1.11, even version 1.51.1 of all builtins ran fine.

I'm not sure, we always used an older version of markdown-language-features since it had issues.
You might have been using @theia/preview functionality.

[Jarthianur]

Ok works again with 1.39.2.

Is there any reason for especially this extension to be not compatible in a newer version?

[vince-fugnitto]

Is there any reason for especially this extension to be not compatible in a newer version?

@Jarthianur for one, there is the following issue #8752, which will likely require a bigger change for monaco-editor.

[vince-fugnitto]

Ok works again with 1.39.2.

Closing as there is no regression for webviews in 1.12.0. The issue about uri.joinPath is already being tracked in #8752 which should allow newer versions of the builtin being used.