If anyone is using SketchUp 2024 and Voronoi plugin stops working, then delauney3.rb file must be edited and any occurence of "TRUE" and "FALSE" should be replaced with "true" and "false". Like in this example:

triang[0] = [p1 - 1, p2 - 1, p3 - 1]
complete[0] = FALSE
ntri = 1

should become

triang[0] = [p1 - 1, p2 - 1, p3 - 1]
complete[0] = false
ntri = 1

Cheers!