Error(s) in re-building vignettes:
--- re-building ‘GADMTools_GRAPHICS.Rmd’ using rmarkdown
Loading required package: sp
Loading required package: classInt
Loading required package: sf
Linking to GEOS 3.7.2, GDAL 2.4.2, PROJ 5.2.0
Loading required package: rgdal
rgdal: version: 1.4-8, (SVN revision 845)
 Geospatial Data Abstraction Library extensions to R successfully loaded
 Loaded GDAL runtime: GDAL 2.4.2, released 2019/06/28
 Path to GDAL shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/gdal
 GDAL binary built with GEOS: FALSE 
 Loaded PROJ.4 runtime: Rel. 5.2.0, September 15th, 2018, [PJ_VERSION: 520]
 Path to PROJ.4 shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/proj
 Linking to sp version: 1.4-1 

Attaching package: 'GADMTools'

The following object is masked from 'package:utils':

    vignette

Joining, by = "NAME_4"
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'GADMTools_GRAPHICS.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘GADMTools_GRAPHICS.Rmd’

--- re-building ‘GADMTools_ISO_3166-1_alpha-3.Rmd’ using rmarkdown
Loading required package: sp
Loading required package: classInt
Loading required package: sf
Linking to GEOS 3.7.2, GDAL 2.4.2, PROJ 5.2.0
Loading required package: rgdal
rgdal: version: 1.4-8, (SVN revision 845)
 Geospatial Data Abstraction Library extensions to R successfully loaded
 Loaded GDAL runtime: GDAL 2.4.2, released 2019/06/28
 Path to GDAL shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/gdal
 GDAL binary built with GEOS: FALSE 
 Loaded PROJ.4 runtime: Rel. 5.2.0, September 15th, 2018, [PJ_VERSION: 520]
 Path to PROJ.4 shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/proj
 Linking to sp version: 1.4-1 

Attaching package: 'GADMTools'

The following object is masked from 'package:utils':

    vignette

dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'GADMTools_ISO_3166-1_alpha-3.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘GADMTools_ISO_3166-1_alpha-3.Rmd’

--- re-building ‘GADMTools_Manipulating_Shapefiles.Rmd’ using rmarkdown
Loading required package: sp
Loading required package: classInt
Loading required package: sf
Linking to GEOS 3.7.2, GDAL 2.4.2, PROJ 5.2.0
Loading required package: rgdal
rgdal: version: 1.4-8, (SVN revision 845)
 Geospatial Data Abstraction Library extensions to R successfully loaded
 Loaded GDAL runtime: GDAL 2.4.2, released 2019/06/28
 Path to GDAL shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/gdal
 GDAL binary built with GEOS: FALSE 
 Loaded PROJ.4 runtime: Rel. 5.2.0, September 15th, 2018, [PJ_VERSION: 520]
 Path to PROJ.4 shared files: /Volumes/Builds/packages/high-sierra-x86_64/Rlib/4.0/rgdal/proj
 Linking to sp version: 1.4-1 

Attaching package: 'GADMTools'

The following object is masked from 'package:utils':

    vignette

Warning: attribute variables are assumed to be spatially constant throughout all geometries
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'GADMTools_Manipulating_Shapefiles.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘GADMTools_Manipulating_Shapefiles.Rmd’

SUMMARY: processing the following files failed:
  ‘GADMTools_GRAPHICS.Rmd’ ‘GADMTools_ISO_3166-1_alpha-3.Rmd’
  ‘GADMTools_Manipulating_Shapefiles.Rmd’

Error: Vignette re-building failed.
Execution halted