Error(s) in re-building vignettes:
--- re-building ‘Building_a_module.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.
Error: processing vignette 'Building_a_module.Rmd' failed with diagnostics:
unable to load shared object '/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so':
  dlopen(/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so
  Reason: image not found
--- failed re-building ‘Building_a_module.Rmd’

--- re-building ‘basic-zoon-usage.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.
Error: processing vignette 'basic-zoon-usage.Rmd' failed with diagnostics:
unable to load shared object '/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so':
  dlopen(/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so
  Reason: image not found
--- failed re-building ‘basic-zoon-usage.Rmd’

--- re-building ‘interactive_zoon_usage.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.
Error: processing vignette 'interactive_zoon_usage.Rmd' failed with diagnostics:
unable to load shared object '/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so':
  dlopen(/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.6/stringi/libs/stringi.so
  Reason: image not found
--- failed re-building ‘interactive_zoon_usage.Rmd’

SUMMARY: processing the following files failed:
  ‘Building_a_module.Rmd’ ‘basic-zoon-usage.Rmd’
  ‘interactive_zoon_usage.Rmd’

Error: Vignette re-building failed.
Execution halted