Repository: vscode
Issue: removing `editor.defaultFormatter` with "Settings" shows red error popup
Labels: bug,settings-editor,confirmed

Type: <b>Bug</b>

If `editor.defaultFormatter` is modified in __JavaScript > User__, removing it causes a red error popup message.
The message displayed is `Setting has an invalid type, expected ["string","null"]. Fix in JSON.`
This behavior occurs even if all extension is disabled.

Preparation (not directly related to this bug):
1. Install new JavaScript formatters (I installed Prettier).
2. Try to format js file.
3. A "Configure Default Formatter" prompt appears.
4. Select any formatter and automatically set `editor.defaultFormatter` in User [JavaScript].

Steps to reproduce:
1. Open "Settings".
2. Search for `editor.defaultFormatter` with the query `@id:editor.defaultFormatter @lang:javascript defaultFo`.
3. Something is selected, so change it to "None".
4. Click on any empry area and get out of the select box.
5. Red popup `Setting has an invalid type, expected ["string","null"]. Fix in JSON.` appears.

Screen shot:
![](https://user-images.githubusercontent.com/88940383/216681150-0f98940b-817b-45c7-a487-0124109f1cec.png)

Video:
https://user-images.githubusercontent.com/88940383/214889081-e7349c73-a11b-492e-b7dc-e430e723cfda.mp4

----

VS Code version: Code 1.74.3 (97dec172d3256f8ca4bfb2143f3f76b503ca0534, 2023-01-09T16:59:02.252Z)
OS version: Windows_NT x64 10.0.19044
Modes:
Sandboxed: No

<details>
<summary>System Info</summary>

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (8 x 3408)|
|GPU Status|2d_canvas: enabled<br>canvas_oop_rasterization: disabled_off<br>direct_rendering_display_compositor: disabled_off_ok<br>gpu_compositing: enabled<br>multiple_raster_threads: enabled_on<br>opengl: enabled_on<br>rasterization: enabled<br>raw_draw: disabled_off_ok<br>skia_renderer: enabled_on<br>video_decode: enabled<br>video_encode: enabled<br>vulkan: disabled_off<br>webgl: enabled<br>webgl2: enabled<br>webgpu: disabled_off|
|Load (avg)|undefined|
|Memory (System)|7.90GB (1.02GB free)|
|Process Argv|--crash-reporter-id 9963c767-2656-4ecc-b62b-9405d4b964a1|
|Screen Reader|no|
|VM|0%|
</details><details><summary>Extensions (46)</summary>

Extension|Author (truncated)|Version
---|---|---
Bookmarks|ale|13.3.1
vscode-intelephense-client|bme|1.9.4
multi-cursor-case-preserve|Car|1.0.5
path-intellisense|chr|2.8.4
gitignore|cod|0.9.0
jsdoc-generator|cry|1.1.1
vscode-eslint|dba|2.2.6
githistory|don|0.6.19
gitlens|eam|13.2.0
prettier-vscode|esb|9.10.4
vscode-firefox-debug|fir|2.9.8
codespaces|Git|1.13.7
remotehub|Git|0.48.0
vscode-edit-csv|jan|0.7.2
vscode-peacock|joh|4.2.2
vsc-python-indent|Kev|1.18.0
flexible-zenkaku|low|0.0.1
line-merge|maf|1.0.2
rainbow-csv|mec|3.5.0
vscode-filesize|mkx|3.1.0
vscode-language-pack-ja|MS-|1.74.12140928
isort|ms-|2022.8.0
python|ms-|2022.20.2
vscode-pylance|ms-|2023.1.40
jupyter|ms-|2022.11.1003412109
jupyter-keymap|ms-|1.0.0
jupyter-renderers|ms-|1.0.14
vscode-jupyter-cell-tags|ms-|0.1.6
vscode-jupyter-slideshow|ms-|0.1.5
azure-repos|ms-|0.24.0
live-server|ms-|0.4.4
remote-repositories|ms-|0.26.0
sftp|Nat|1.16.1
autodocstring|njp|0.6.1
merge-n-paste|RAW|1.3.7
svg-preview|Sim|2.8.3
code-spell-checker|str|2.15.0
vscode-input-sequence|tom|0.2.0
vscode-counter|uct|3.2.0
reopenclosedtab|uyi|1.1.0
intellicode-api-usage-examples|Vis|0.2.7
vscodeintellicode|Vis|1.2.30
change-case|wma|1.0.0
zoombar-vscode|wra|1.4.2
php-debug|xde|1.30.0
cursor-align|yo1|1.1.0


</details><details>
<summary>A/B Experiments</summary>

```
vsliv368:30146709
vsreu685:30147344
python383:30185418
vspor879:30202332
vspor708:30202333
vspor363:30204092
vstes627:30244334
vslsvsres303:30308271
pythonvspyl392:30443607
vserr242cf:30382550
pythontb:30283811
vsjup518:30340749
pythonptprofiler:30281270
vshan820:30294714
vstes263:30335439
vscoreces:30445986
pythondataviewer:30285071
vscod805:30301674
binariesv615:30325510
bridge0708:30335490
bridge0723:30353136
cmake_vspar411:30581797
vsaa593cf:30376535
pythonvs932:30410667
cppdebug:30492333
vsclangdf:30486550
c4g48928:30535728
dsvsc012cf:30540253
azure-dev_surveyone:30548225
pyindex848cf:30577861
nodejswelcome1:30587005
3biah626:30602489
f6dab269:30613381
pythonsymbol12:30652348
2i9eh265:30646982

```

</details>

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