wip: fix view container 'null' error

[vince-fugnitto]

What it does

Fixes #6231

Set the ViewContainerLayout explicitly so it is not null when it is being used.

How to test

Re-test the following functionality present in #5665

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

Signed-off-by: Vincent Fugnitto vincent.fugnitto@ericsson.com

[vince-fugnitto]

I meant to create a draft PR but it looked like Github had a slight hiccup.
I'm wondering if this is the correct approach to fixing the issue where the ViewContainer layout may be null, or if explicit type checks should be added to ensure it is not.

[akosyakov]

I don't understand how it can be null: init is called before any other call and it sets panel and its layout.

[kittaakos]

ViewContainer layout may be null

I cannot reproduce it anymore. Does anyone know the exact steps?

[svenefftinge]

This fixes only the symptom not the underlying problem, which is those widgets are disposed (widget dispose nulls the layout).
A parent gets disposed here:
https://github.com/eclipse-theia/theia/blob/master/packages/plugin-ext/src/main/browser/view/plugin-view-registry.ts#L410
which disposes all its children.

[kittaakos]

Does anyone know the exact steps?

Open the Plugins view and refresh the browser.

I can see, there is a view container with test ID. I do not yet see where does it come from:

Strangely, there is only one test view container registered:

[kittaakos]

Got it finally, the exception is thrown because Test view is not opened. We do not see the same error for SCM and Debug because both views are opened and initialized as part of the default application shell layout.

I can confirm, the error is gone if I open the Test view, and I refresh the browser while the Plugins view is the active widget on the left-hand side.

This fixes only the symptom not the underlying problem

I second this. We need another fix.

[vince-fugnitto]

@kittaakos @svenefftinge thanks for helping find the root cause, I initially wanted to have the PR as a draft specifically for that reason.

I don't quite understand why the container has to be disposed on initWidgets.

[akosyakov]

@vince-fugnitto On new deployment a plugin can be removed then its views and view containers should be removed. You can reproduce it by stopping a server, removing a plugin contributing a view and starting a server. A client should reconnect and remove view containers. Apparently we don't remove all references to view container afterwards.

[vince-fugnitto]

@vince-fugnitto On new deployment a plugin can be removed then its views and view containers should be removed. You can reproduce it by stopping a server, removing a plugin contributing a view and starting a server. A client should reconnect and remove view containers. Apparently we don't remove all references to view container afterwards.

Thank you for the clarification :)