e.show is not a function

[isidorn]

Refs: #91335

1. Take the watch view and drop it into the panel
2. Drag the watch view and drop it into the Extensions viewlet icon in activity bar
3. Extensions viewlet gets broken -> there is an error in the developer tools console 🐛

Reload does not fix the issue -> it would be great if we fix this issue this milestone.
Call stack

RR e.show is not a function: TypeError: e.show is not a function
    at file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:6372:803
    at Array.map (<anonymous>)
    at ae.onDidAddViewDescriptors (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:6372:794)
    at ae.create (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5635:380)
    at ae.create (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:6368:434)
    at t.create (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3399:1008)
    at e.showComposite (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5147:974)
    at e.doOpenComposite (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5146:870)
    at e.openComposite (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5146:402)
    at e.doOpenViewlet (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5716:343)
    at e.openViewlet (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5715:675)
    at t.CompositeDragAndDrop.openComposite (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5680:434)
    at t.CompositeDragAndDrop.drop (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5665:155)
    at Object.onDrop (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5652:843)
    at HTMLLIElement.<anonymous> (file:///Applications/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:5538:528)

[sbatten]

fyi @sandy081, fixed by adding flag to container descriptor that rejects adding views. necessary for extensions viewlet.