I cannot accept the PR as you changed the tests for drawing relative motion vectors.
There are 2 style properties:
style.courseVector (true|false)
style.courseVectorColor (color)
See https://www.wellenvogel.net/software/avnav/docs/hints/usericons.html?lang=en#h2:AISImages
For testing whether to draw vectors the first one must be used.
I guess we even would have to check if "useCourseVector" is active at all (basically disabling this could improve the performance on very slow displays).

OK, now I understand the somewhat strange expression style.courseVector !== false because courseVector can be (and is) undefined. The breaking change was, that target.distance now is in meters.

I adjusted the conditions to check for useCourseVector && style.courseVector !== false first.

in current master the aisRelativeMotionVectorRange is missing.

A typo, fixed it in 839e30f