Error(s) in re-building vignettes:
--- re-building ‘introduction.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) 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


Attaching package: 'magrittr'

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

    set_names

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

    extract


Attaching package: 'gridExtra'

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

    combine

Joining, by = "scenario"
Joining, by = "scenario"
Warning: `filter_()` was deprecated in dplyr 0.7.0.
Please use `filter()` instead.
See vignette('programming') for more help
This warning is displayed once every 8 hours.
Call `lifecycle::last_warnings()` to see where this warning was generated.
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Helvetica" could not be found for family "sans"
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  :
  font "Helvetica" could not be found for family "sans"
Quitting from lines 154-155 (introduction.Rmd) 
Error: processing vignette 'introduction.Rmd' failed with diagnostics:
polygon edge not found
--- failed re-building ‘introduction.Rmd’

SUMMARY: processing the following file failed:
  ‘introduction.Rmd’

Error: Vignette re-building failed.
Execution halted