Error(s) in re-building vignettes:
--- re-building 'icosa.Rmd' using rmarkdown
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in oldviewport$viewport * newsize :
  NAs produced by integer overflow
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Quitting from lines 318-326 (icosa.Rmd) 
Error: processing vignette 'icosa.Rmd' failed with diagnostics:
missing value where TRUE/FALSE needed
--- failed re-building 'icosa.Rmd'

SUMMARY: processing the following file failed:
  'icosa.Rmd'

Error: Vignette re-building failed.
In addition: Warning messages:
1: In snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
2: In oldviewport$viewport * newsize : NAs produced by integer overflow
3: In snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
4: In snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
5: In snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Execution halted