Error(s) in re-building vignettes:
  ...
--- re-building ‘bi-objective_2x.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Warning: ggrepel: 70 unlabeled data points (too many overlaps). Consider increasing max.overlaps
Warning: ggrepel: 70 unlabeled data points (too many overlaps). Consider increasing max.overlaps
Warning: ggrepel: 70 unlabeled data points (too many overlaps). Consider increasing max.overlaps
Warning: ggrepel: 70 unlabeled data points (too many overlaps). Consider increasing max.overlaps
--- finished re-building ‘bi-objective_2x.Rmd’

--- re-building ‘bi-objective_3x_ex1.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Quitting from lines 84-85 (bi-objective_3x_ex1.Rmd) 
Error: processing vignette 'bi-objective_3x_ex1.Rmd' failed with diagnostics:
invalid 'path' argument
--- failed re-building ‘bi-objective_3x_ex1.Rmd’

--- re-building ‘intro.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Quitting from lines 146-155 (intro.Rmd) 
Error: processing vignette 'intro.Rmd' failed with diagnostics:
invalid 'path' argument
--- failed re-building ‘intro.Rmd’

--- re-building ‘polytope_2d.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘polytope_2d.Rmd’

--- re-building ‘polytope_3d_ex1.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Quitting from lines 58-60 (polytope_3d_ex1.Rmd) 
Error: processing vignette 'polytope_3d_ex1.Rmd' failed with diagnostics:
invalid 'path' argument
--- failed re-building ‘polytope_3d_ex1.Rmd’

--- re-building ‘tri-objective.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Quitting from lines 44-59 (tri-objective.Rmd) 
Error: processing vignette 'tri-objective.Rmd' failed with diagnostics:
invalid 'path' argument
--- failed re-building ‘tri-objective.Rmd’

SUMMARY: processing the following files failed:
  ‘bi-objective_3x_ex1.Rmd’ ‘intro.Rmd’ ‘polytope_3d_ex1.Rmd’
  ‘tri-objective.Rmd’

Error: Vignette re-building failed.
Execution halted