Error(s) in re-building vignettes:
--- re-building ‘PPforest-vignette.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
Loading required package: PPforest
Loading required package: dplyr

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

Loading required package: RColorBrewer
Loading required package: GGally
Loading required package: ggplot2
Loading required package: gridExtra

Attaching package: 'gridExtra'

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

    combine

Loading required package: PPtreeViz
Loading required package: partykit
Loading required package: grid
Loading required package: libcoin
Loading required package: mvtnorm
Loading required package: Rcpp
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)) :
  font "Times-Roman" could not be found for family "serif"
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  :
  font "Times-Roman" could not be found for family "serif"
Quitting from lines 118-129 (PPforest-vignette.Rmd) 
Error: processing vignette 'PPforest-vignette.Rmd' failed with diagnostics:
polygon edge not found
--- failed re-building ‘PPforest-vignette.Rmd’

SUMMARY: processing the following file failed:
  ‘PPforest-vignette.Rmd’

Error: Vignette re-building failed.
Execution halted