Error(s) in re-building vignettes:
  ...
--- re-building ‘cycling-potential-uk.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.
Linking to GEOS 3.6.3, GDAL 2.2.4, PROJ 5.2.0

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Warning: replacing previous import 'sf::st_make_valid' by 'lwgeom::st_make_valid' when loading 'tmap'
--- finished re-building ‘cycling-potential-uk.Rmd’

--- re-building ‘pct-international.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.
Quitting from lines 109-116 (pct-international.Rmd) 
Error: processing vignette 'pct-international.Rmd' failed with diagnostics:
there is no package called 'webshot'
--- failed re-building ‘pct-international.Rmd’

--- re-building ‘pct.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.
Quitting from lines 169-175 (pct.Rmd) 
Error: processing vignette 'pct.Rmd' failed with diagnostics:
there is no package called 'webshot'
--- failed re-building ‘pct.Rmd’

--- re-building ‘pct_training.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.

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

tmap mode set to interactive viewing
Linking to GEOS 3.6.3, GDAL 2.2.4, PROJ 5.2.0
Legend for line widths not available in view mode.
Quitting from lines 113-133 (pct_training.Rmd) 
Error: processing vignette 'pct_training.Rmd' failed with diagnostics:
there is no package called 'webshot'
--- failed re-building ‘pct_training.Rmd’

SUMMARY: processing the following files failed:
  ‘pct-international.Rmd’ ‘pct.Rmd’ ‘pct_training.Rmd’

Error: Vignette re-building failed.
Execution halted