Error(s) in re-building vignettes:
  ...
--- re-building ‘osem-history.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


Attaching package: 'lubridate'

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

    date


Attaching package: 'zoo'

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

    as.Date, as.Date.numeric

Warning in bind_rows_(x, .id) :
  Unequal factor levels: coercing to character
Warning in bind_rows_(x, .id) :
  binding character and factor vector, coercing into character vector
Warning in bind_rows_(x, .id) :
  binding character and factor vector, coercing into character vector
Warning: Removed 5 rows containing missing values (geom_path).
Don't know how to automatically pick scale for object of type difftime. Defaulting to continuous.
Don't know how to automatically pick scale for object of type difftime. Defaulting to continuous.
Don't know how to automatically pick scale for object of type difftime. Defaulting to continuous.
--- finished re-building ‘osem-history.Rmd’

--- re-building ‘osem-intro.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.
Loading required package: maps
Loading required package: maptools
Loading required package: sp
Checking rgeos availability: TRUE
Loading required package: rgeos
rgeos version: 0.4-3, (SVN revision 595)
 GEOS runtime version: 3.6.3-CAPI-1.10.3 
 Linking to sp version: 1.3-1 
 Polygon checking: TRUE 

Quitting from lines 85-90 (osem-intro.Rmd) 
Error: processing vignette 'osem-intro.Rmd' failed with diagnostics:
parse error: premature EOF
                                       [{"_id":"5710de1a45fd40c8198cce
                     (right here) ------^

--- failed re-building ‘osem-intro.Rmd’

--- re-building ‘osem-serialization.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.
--- finished re-building ‘osem-serialization.Rmd’

SUMMARY: processing the following file failed:
  ‘osem-intro.Rmd’

Error: Vignette re-building failed.
Execution halted