public void dispose() {
		if (markerService != null) {
			markerService.removeMarker(markerSet, bookmarkMgr.getProgram());
			markerSet = null;
			bookmarkMgr = null;
		}
	}
Get rid of any local resource connections before this object is disposed of.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/bookmark/BookmarkNavigator.java