Switching themes causes webview Error

[lramos15]

Issue Type: Bug

1. Toggle developer tools
2. Switch themes

Everything appears to work as normal, but the console gets flooded with WebView must be attached to the DOM and the dom-ready event emitted before this method can be called. errors.

VS Code version: Code - Insiders 1.36.0-insider (15b7c86, 2019-06-14T10:36:51.530Z)
OS version: Darwin x64 18.6.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz (12 x 2600)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: enabled oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_deferred_display_list: disabled_off skia_renderer: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: disabled_off webgl: enabled webgl2: enabled
Load (avg)	2, 2, 2
Memory (System)	32.00GB (9.96GB free)
Process Argv	-psn_0_2441812
Screen Reader	no
VM	0%

Extensions (13)

Extension	Author (truncated)	Version
vscode-eslint	dba	1.9.0
gitlens	eam	9.8.2
vsc-material-theme	Equ	2.9.0
remote-containers	ms-	0.61.0
remote-ssh-edit-nightly	ms-	2019.6.19620
remote-ssh-explorer-nightly	ms-	2019.6.19620
remote-ssh-nightly	ms-	2019.6.18180
vscode-typescript-tslint-plugin	ms-	1.1.0
debugger-for-chrome	msj	4.11.3
vscode-docker	Pet	0.6.2
material-icon-theme	PKi	3.8.0
polacode	pnp	0.3.2
vscode-sort-json	ric	1.13.0

[mjbvz]

I can't repo this. Which developer tools and theme are you talking about specifically?

[lramos15]

I tried repoing this again and it appears that this error is related to installing a new theme.
Here are some better repo steps:

1. Toggle developer tools
2. Switch themes (no errors)
3. Install a theme
4. Switch themes (errors even if it is one of the themes shipped with VS code)

The errors go away after a reload, but installing a theme does not tell me a reload is required.

[mjbvz]

Ok, with the extensions view open, I sometimes see

ERR Invalid guestInstanceId: null: Error: Invalid guestInstanceId: null
    at Object.getGuestForWebContents (/Applications/Visual Studio Code - Insiders.app/Contents/Resources/electron.asar/browser/guest-view-manager.js:430:11)
    at /Applications/Visual Studio Code - Insiders.app/Contents/Resources/electron.asar/browser/rpc-server.js:449:34
    at EventEmitter.ipcMain.on.args (/Applications/Visual Studio Code - Insiders.app/Contents/Resources/electron.asar/browser/rpc-server.js:278:21)
    at EventEmitter.emit (events.js:182:13)
    at WebContents.<anonymous> (/Applications/Visual Studio Code - Insiders.app/Contents/Resources/electron.asar/browser/api/web-contents.js:370:21)
    at WebContents.emit (events.js:182:13)

Does not cause seem to cause any actual problems

[lramos15]

I get that as well sometimes, but do you not get the webview must be attached to the DOM error as well?

[jeanp413]

I can reproduce it. Steps:

1. Click on any extension to load it's Readme in an editor
2. Close that editor
3. Change theme (this triggers the webview error)
4. Repeat step 1 (this triggers the guestInstanceId error)