ERR: View resolver already registered for <viewId>

[bcanzanella]

VSCode Version:
Version: 1.50.0 (user setup)
Commit: 93c2f0f
Date: 2020-10-07T06:10:52.432Z
Electron: 9.2.1
Chrome: 83.0.4103.122
Node.js: 12.14.1
V8: 8.3.110.13-electron.0
OS: Windows_NT x64 10.0.19041

Steps to Reproduce:

1. My fork has the changes to reproduce this. https://github.com/microsoft/vscode-extension-samples/compare/master...bcanzanella:already-registered-issue?expand=1 it's just a couple of package.json changes (and an svg [meow!?])

2. There's some combination of loading/reloading the extension and adding a folder to the workspace which creates ERR View resolver already registered for calicoColors.colorsView. I can consistently get it to happen with CodeStream by ensuring I don't have a workspace open, adding a folder to the workspace, and clicking the icon in the activity bar to open the webview. That doesn't seem to work 100% of the time with the calico cat example, but after a couple of times it seems to happen.

It doesn't appear to affect the sample's webview except for the error in the console, but when this happens with CodeStream our webview is dead (see attached).

My first guess is perhaps the registerWebviewViewProvider is somehow not disposing correctly? (even though it's in the context.subscriptions array...)

Does this issue occur when all extensions are disabled?: N/A

[mjbvz]

The new behavior should now be:

1. Starting with a single folder
2. Webview view created
3. User adds folder to create a workspace
4. Extension host restarts.
5. This should restart the extension and also clear the old webview view
6. We should then try re-resolve the new webview view with the new extension host

[github-actions]

This bug has been fixed in to the latest release of VS Code Insiders!

@bcanzanella, you can help us out by confirming things are working as expected in the latest Insiders release. If things look good, please leave a comment with the text /verified to let us know. If not, please ensure you're on version 2ee8b8c of Insiders (today's or later - you can use Help: About in the command pallete to check), and leave a comment letting us know what isn't working as expected.

Happy Coding!

[bcanzanella]

/verified