Fix Warning: 'rgl.init' failed, running with 'rgl.useNULL = TRUE' durig build

[markheckmann]

The warning you're encountering during the R CMD CHECK process, specifically "Warning: 'rgl.init' failed, running with 'rgl.useNULL = TRUE'", typically indicates an issue with the initialization of the RGL package, which is used for 3D visualizations in R. This often happens in environments where a proper graphical display is not available, such as on headless servers or during automated testing like R CMD CHECK.