Error(s) in re-building vignettes:
--- re-building ‘dev.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.
--- finished re-building ‘dev.Rmd’

--- re-building ‘examples2d.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.
--- finished re-building ‘examples2d.Rmd’

--- re-building ‘examples3d1.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.

Quitting from lines 58-61 [unnamed-chunk-4] (examples3d1.Rmd)
Error: processing vignette 'examples3d1.Rmd' failed with diagnostics:
Saving a widget with selfcontained = TRUE requires pandoc. See here to learn more https://bookdown.org/yihui/rmarkdown-cookbook/install-pandoc.html
--- failed re-building ‘examples3d1.Rmd’

--- re-building ‘examples3d2.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.

Quitting from lines 58-61 [unnamed-chunk-4] (examples3d2.Rmd)
Error: processing vignette 'examples3d2.Rmd' failed with diagnostics:
Saving a widget with selfcontained = TRUE requires pandoc. See here to learn more https://bookdown.org/yihui/rmarkdown-cookbook/install-pandoc.html
--- failed re-building ‘examples3d2.Rmd’

--- re-building ‘examplesmrg.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.
--- finished re-building ‘examplesmrg.Rmd’

--- re-building ‘examplesnd.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.
--- finished re-building ‘examplesnd.Rmd’

--- re-building ‘theory.Rmd’ using rmarkdown
Pandoc is required to build R Markdown vignettes but not available. Please make sure it is installed.
--- finished re-building ‘theory.Rmd’

SUMMARY: processing the following files failed:
  ‘examples3d1.Rmd’ ‘examples3d2.Rmd’

Error: Vignette re-building failed.
Execution halted