Error(s) in re-building vignettes:
  ...
--- re-building ‘bayesian.Rmd’ using rmarkdown
Loading required package: Rcpp
rstanarm (Version 2.18.2, packaged: 2018-11-08 22:19:38 UTC)
- Do not expect the default priors to remain the same in future rstanarm versions.
Thus, R scripts should specify priors explicitly, even if they are just the defaults.
- For execution on a local, multicore CPU with excess RAM we recommend calling
options(mc.cores = parallel::detectCores())
- Plotting theme set to bayesplot::theme_default().

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

Warning: replacing previous import 'loo::kfold' by 'rstanarm::kfold' when loading 'psycho'
Quitting from lines 88-111 (bayesian.Rmd) 
Error: processing vignette 'bayesian.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘bayesian.Rmd’

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

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: Rcpp
rstanarm (Version 2.18.2, packaged: 2018-11-08 22:19:38 UTC)
- Do not expect the default priors to remain the same in future rstanarm versions.
Thus, R scripts should specify priors explicitly, even if they are just the defaults.
- For execution on a local, multicore CPU with excess RAM we recommend calling
options(mc.cores = parallel::detectCores())
- Plotting theme set to bayesplot::theme_default().
Scale for 'fill' is already present. Adding another scale for 'fill',
which will replace the existing scale.
Quitting from lines 119-138 (overview.Rmd) 
Error: processing vignette 'overview.Rmd' failed with diagnostics:
VECTOR_ELT() can only be applied to a 'list', not a 'double'
--- failed re-building ‘overview.Rmd’

SUMMARY: processing the following files failed:
  ‘bayesian.Rmd’ ‘overview.Rmd’

Error: Vignette re-building failed.
Execution halted