Error in re-building vignettes:
  ...
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'

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    filter, lag

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

    intersect, setdiff, setequal, union


Attaching package: 'tidyr'

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

    extract

NOTE: As of tidybayes version 1.0, several functions, arguments, and output column names
      have undergone significant name changes in order to adopt a unified naming scheme.
      See help('tidybayes-deprecated') for more information.


Attaching package: 'ggstance'

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    GeomErrorbarh, geom_errorbarh


Attaching package: 'ggridges'

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    scale_discrete_manual


Attaching package: 'cowplot'

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    ggsave

Loading required package: StanHeaders
rstan (Version 2.18.1, GitRev: 2e1f913d3ca3)
For execution on a local, multicore CPU with excess RAM we recommend calling
options(mc.cores = parallel::detectCores()).
To avoid recompilation of unchanged Stan programs, we recommend calling
rstan_options(auto_write = TRUE)

Attaching package: 'rstan'

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    extract

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    extract

Loading required package: Rcpp
Loading 'brms' package (version 2.5.0). Useful instructions
can be found by typing help('brms'). A more detailed introduction
to the package is available through vignette('brms_overview').
Run theme_set(theme_default()) to use the default bayesplot theme.

Attaching package: 'brms'

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    loo

Quitting from lines 59-77 (tidy-brms.Rmd) 
Error: processing vignette 'tidy-brms.Rmd' failed with diagnostics:
object 'params' not found
Execution halted