iNAV freezes activeWaypointIndex at whatever mission waypoint was
active when RTH engaged instead of updating it to reflect the new
target - navigation.c derives NAV_Status.activeWpIndex unconditionally
from posControl.activeWaypointIndex, and none of the RTH state-entry
handlers touch that field. Drawing the guidance line to that stale
index would point at a waypoint the aircraft may have already passed.
Extracted the target selection into computeRubberBandTarget() (mission
stats.dart) so the RTH special-case and the abort-back-to-waypoint-mode
fallback are unit-tested rather than only living inline in the widget
build method - since it re-evaluates navMode on every frame, aborting
RTH switches the line back to the mission waypoint with no extra
transition logic needed.
Constantin Leue
afc380cabc