crashes in No Alignment mode

[cannam]

1. Open Sonic Lineup and load a session with multiple files in it (with some alignment mode active, presumably)
2. Go to Alignment menu and switch to No Alignment
3. Exit Sonic Lineup and restart it (re-opening the same session automatically)
4. Add a new audio file
5. Sonic Lineup crashes

Crash is in

#1  0x00005555557fc321 in MainWindow::mapSalientFeatureLayer(TypedId<Model>) ()
#2  0x00005555557f78a4 in MainWindow::mapAllSalientFeatureLayers() ()
#3  0x00005555557fe95b in MainWindow::openFiles() ()

[cannam]

(It is also possible to produce this crash by other means, e.g. re-selecting No Alignment when it has already been selected.)