Settings -> Track List Columns listed two rows both called "Track
Name", one of which could not be ticked, and a screen reader heard
"Show the Track Name column" twice with nothing to tell them apart.
They are `titleArtist` and `trackName`, and the issue left open which
way to fix it: a second label so the sort dropdown and the configurator
can say different words, or drop the row because the user cannot select
it. The code settles that. `titleArtist` is not in
`tracklist.AllColumnIDs`, so `Config.Validate()` returns `unknown
track-list column ID: "titleArtist"` -- ticking the row sends a column
set the backend rejects, `config-page` swallows the rejection into a
`console.error`, and the tick reverts. A second label would have named
a control that cannot work.
So a definition says whether it is a *choice*, and the configurator
reads `CONFIGURABLE_COLUMN_IDS` rather than `Object.keys(COLUMN_DEFS)`.
The new test reads Go's own list out of `backend/tracklist/config.go`
rather than writing it down a third time, since a third copy is the
fault one step earlier. Verified by planting: with the filter removed
all four assertions fail with the defect's own numbers.
Not fixed here, and filed as #231: `SetTrackListColumns` assigns before
it validates, so a rejected list stays in memory and `Save()` validates
the whole config -- one tick and no setting saves for the rest of the
session. That is reachable from any invalid input, not from this row.
Closes#197
logan
d225f922fb