homePage is set to the empty string when editing a configuration

Reproduction steps

1. start electron
2. edit a configuration where homePage is not defined
3. change an unrelated value (e.g., the editor)
4. save the config
5. inspect the content

Expected

Only the value of the editor field is changed

Actual

A lot of values are initialized to the empty string instead of staying undefined.

For instance, before modification, the config was

"FileSystem": {
  "name": "FileSystem",
  "configType": "FileSystem",
  "serverRendering": false,
  "offline": false,
  "designSystem": "vuetify",
  "editor": "tiptap"
} 

And is like below after save. Notice the baseURL, baseRestURL, homePage, storageRoot and realtimeURL initialized to the empty string.

"FileSystem": {
  "name": "FileSystem",
  "configType": "FileSystem",
  "serverRendering": false,
  "offline": false,
  "designSystem": "vuetify",
  "editor": "tiptap"
}