The lazily created DisplayMarker that was emitted in the creation event would be immediately overwritten by a new DisplayMarker during creation.
Calling DisplayMarkerLayer.findMarkers from a DisplayMarker.onDidDestroy callback threw an exception.
Avoid creating duplicate DisplayMarkers
when the DisplayMarkerLayer has onDidCreateMarker observers
Signed-off-by: Nathan Sobo <firstname.lastname@example.org>
Fix exception when findMarkers is called in an onDidDestroy callback