message: Replace `null` with `"null"` for types in the schema
diff: "description": "Sets the file location of the image to draw over the window background when unfocused.",
  "oneOf": [
  {
  - "type": ["string", null]
  + "type": ["string", "null"]
  },
  {
  "enum": [
  "description": "Sets the file location of the image to draw over the window background.",
  "oneOf": [
  {
  - "type": ["string", null]
  + "type": ["string", "null"]
  },
  {
  "enum": [
  