When encountering a nested object property with a trailing comma,
such as `{ "a": { "x": 1, "y": 2, }, "c": 3 }`, the `json/sort` command
would throw the following error:

```
Range#create called with invalid arguments[[object Object], [object Object], undefined, undefined]: Error: Request json/sort failed with message: Range#create called with invalid arguments[[object Object], [object Object], undefined, undefined]
```

The reason is that the sorting code's scanner failed to navigate up to
the parent when `}` after the trailing comma is encountered, because
the condition `currentProperty!.endLineNumber === undefined` for
doing so is false if the previous non-trivia non-comment token was a
comma (`endLineNumber` would have already been set when processing
the comma).

As a consequence, any further properties in the parent object (like
`"c"` in the above example) would be wronly considered to be part of the
preceding nested object, which confuses the scanner and results in the
`endLineNumber` of the last property not being set at all. This, in the
end, triggers the `Range.create()` error when the sorting code attempts
build a range with that undefined end line number.

Fixes microsoft/vscode#178229