Error(s) in re-building vignettes:
--- re-building ‘Additional_Examples.Rmd’ using rmarkdown
! Undefined control sequence.
l.74 \__kernel_quark_new_conditional:Nn
                                        \__xtemplate_quark_if_nil:N { F } 

Error: processing vignette 'Additional_Examples.Rmd' failed with diagnostics:
LaTeX failed to compile /data/gannet/ripley/R/packages/tests-devel/eChem.Rcheck/vign_test/eChem/vignettes/Additional_Examples.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See Additional_Examples.log for more info.
--- failed re-building ‘Additional_Examples.Rmd’

--- re-building ‘Computational_Details.Rmd’ using rmarkdown
! Undefined control sequence.
l.74 \__kernel_quark_new_conditional:Nn
                                        \__xtemplate_quark_if_nil:N { F } 

Error: processing vignette 'Computational_Details.Rmd' failed with diagnostics:
LaTeX failed to compile /data/gannet/ripley/R/packages/tests-devel/eChem.Rcheck/vign_test/eChem/vignettes/Computational_Details.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See Computational_Details.log for more info.
--- failed re-building ‘Computational_Details.Rmd’

--- re-building ‘Overview.Rmd’ using rmarkdown
! Undefined control sequence.
l.74 \__kernel_quark_new_conditional:Nn
                                        \__xtemplate_quark_if_nil:N { F } 

Error: processing vignette 'Overview.Rmd' failed with diagnostics:
LaTeX failed to compile /data/gannet/ripley/R/packages/tests-devel/eChem.Rcheck/vign_test/eChem/vignettes/Overview.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See Overview.log for more info.
--- failed re-building ‘Overview.Rmd’

--- re-building ‘Using_eChem.Rmd’ using rmarkdown
! Undefined control sequence.
l.74 \__kernel_quark_new_conditional:Nn
                                        \__xtemplate_quark_if_nil:N { F } 

Error: processing vignette 'Using_eChem.Rmd' failed with diagnostics:
LaTeX failed to compile /data/gannet/ripley/R/packages/tests-devel/eChem.Rcheck/vign_test/eChem/vignettes/Using_eChem.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See Using_eChem.log for more info.
--- failed re-building ‘Using_eChem.Rmd’

SUMMARY: processing the following files failed:
  ‘Additional_Examples.Rmd’ ‘Computational_Details.Rmd’ ‘Overview.Rmd’
  ‘Using_eChem.Rmd’

Error: Vignette re-building failed.
Execution halted