Error(s) in re-building vignettes:
  ...
--- re-building ‘coxed.Rmd’ using rmarkdown
Loading required package: rms
Loading required package: Hmisc
Loading required package: lattice
Loading required package: survival
Loading required package: Formula
Loading required package: ggplot2

Attaching package: 'Hmisc'

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

    format.pval, units

Loading required package: SparseM

Attaching package: 'SparseM'

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

    backsolve

Loading required package: mgcv
Loading required package: nlme
This is mgcv 1.8-31. For overview type 'help("mgcv-package")'.

Attaching package: 'dplyr'

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

    collapse

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

    src, summarize

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

    filter, lag

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

    intersect, setdiff, setequal, union

--- finished re-building ‘coxed.Rmd’

--- re-building ‘simulating_survival_data.Rmd’ using rmarkdown
Loading required package: rms
Loading required package: Hmisc
Loading required package: lattice
Loading required package: survival
Loading required package: Formula
Loading required package: ggplot2

Attaching package: 'Hmisc'

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

    format.pval, units

Loading required package: SparseM

Attaching package: 'SparseM'

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

    backsolve

Loading required package: mgcv
Loading required package: nlme
This is mgcv 1.8-31. For overview type 'help("mgcv-package")'.
Quitting from lines 143-145 (simulating_survival_data.Rmd) 
Error: processing vignette 'simulating_survival_data.Rmd' failed with diagnostics:
missing value where TRUE/FALSE needed
--- failed re-building ‘simulating_survival_data.Rmd’

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

Error: Vignette re-building failed.
Execution halted