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

--- re-building ‘b1-setting-up-and-using-rix-on-linux-and-windows.Rmd’ using rmarkdown
--- finished re-building ‘b1-setting-up-and-using-rix-on-linux-and-windows.Rmd’

--- re-building ‘b2-setting-up-and-using-rix-on-macos.Rmd’ using rmarkdown
--- finished re-building ‘b2-setting-up-and-using-rix-on-macos.Rmd’

--- re-building ‘c-using-rix-to-build-project-specific-environments.Rmd’ using rmarkdown
--- finished re-building ‘c-using-rix-to-build-project-specific-environments.Rmd’

--- re-building ‘d1-installing-r-packages-in-a-nix-environment.Rmd’ using rmarkdown
--- finished re-building ‘d1-installing-r-packages-in-a-nix-environment.Rmd’

--- re-building ‘d2-installing-system-tools-and-texlive-packages-in-a-nix-environment.Rmd’ using rmarkdown
--- finished re-building ‘d2-installing-system-tools-and-texlive-packages-in-a-nix-environment.Rmd’

--- re-building ‘e-interactive-use.Rmd’ using rmarkdown
--- finished re-building ‘e-interactive-use.Rmd’

--- re-building ‘z-advanced-topic-building-an-environment-for-literate-programming.Rmd’ using rmarkdown
--- finished re-building ‘z-advanced-topic-building-an-environment-for-literate-programming.Rmd’

--- re-building ‘z-advanced-topic-handling-packages-with-remote-dependencies.Rmd’ using rmarkdown
--- finished re-building ‘z-advanced-topic-handling-packages-with-remote-dependencies.Rmd’

--- re-building ‘z-advanced-topic-reproducible-analytical-pipelines-with-nix.Rmd’ using rmarkdown

Quitting from lines 36-54 [unnamed-chunk-3] (z-advanced-topic-reproducible-analytical-pipelines-with-nix.Rmd)
Error: processing vignette 'z-advanced-topic-reproducible-analytical-pipelines-with-nix.Rmd' failed with diagnostics:
non-character argument
--- failed re-building ‘z-advanced-topic-reproducible-analytical-pipelines-with-nix.Rmd’

--- re-building ‘z-advanced-topic-running-r-or-shell-code-in-nix-from-r.Rmd’ using rmarkdown

Quitting from lines 362-372 [unnamed-chunk-9] (z-advanced-topic-running-r-or-shell-code-in-nix-from-r.Rmd)
Error: processing vignette 'z-advanced-topic-running-r-or-shell-code-in-nix-from-r.Rmd' failed with diagnostics:
non-character argument
--- failed re-building ‘z-advanced-topic-running-r-or-shell-code-in-nix-from-r.Rmd’

--- re-building ‘z-advanced-topic-using-nix-inside-docker.Rmd’ using rmarkdown
--- finished re-building ‘z-advanced-topic-using-nix-inside-docker.Rmd’

--- re-building ‘z-binary_cache.Rmd’ using rmarkdown
--- finished re-building ‘z-binary_cache.Rmd’

--- re-building ‘z-bleeding_edge.Rmd’ using rmarkdown
--- finished re-building ‘z-bleeding_edge.Rmd’

--- re-building ‘z-contributing_to_nixpkgs.Rmd’ using rmarkdown
--- finished re-building ‘z-contributing_to_nixpkgs.Rmd’

SUMMARY: processing the following files failed:
  ‘z-advanced-topic-reproducible-analytical-pipelines-with-nix.Rmd’
  ‘z-advanced-topic-running-r-or-shell-code-in-nix-from-r.Rmd’

Error: Vignette re-building failed.
Execution halted