Error(s) in re-building vignettes:
  ...
--- re-building ‘advanced_plotting.Rmd’ using rmarkdown
--- finished re-building ‘advanced_plotting.Rmd’

--- re-building ‘quick_start.Rmd’ using rmarkdown
--- finished re-building ‘quick_start.Rmd’

--- re-building ‘simmr.Rmd’ using rmarkdown

warning: solve(): system is singular; attempting approx solution

Quitting from lines 314-315 [unnamed-chunk-22] (simmr.Rmd)
Error: processing vignette ‘simmr.Rmd’ failed with diagnostics:
solve(): solution not found
--- failed re-building ‘simmr.Rmd’

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

Error: Vignette re-building failed.
Execution halted
installed size is  5.1Mb
  sub-directories of 1Mb or more:
    doc    2.3Mb
    libs   2.5Mb