Error(s) in re-building vignettes:
--- re-building ‘advanced_usage.Rmd’ using rmarkdown

Quitting from lines 31-38 [unnamed-chunk-2] (advanced_usage.Rmd)
Error: processing vignette 'advanced_usage.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘advanced_usage.Rmd’

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

Quitting from lines 42-50 [unnamed-chunk-3] (baseline.Rmd)
Error: processing vignette 'baseline.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘baseline.Rmd’

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

Quitting from lines 65-78 [unnamed-chunk-4] (clinical_trials.Rmd)
Error: processing vignette 'clinical_trials.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘clinical_trials.Rmd’

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

Quitting from lines 58-70 [unnamed-chunk-4] (custom_appearance.Rmd)
Error: processing vignette 'custom_appearance.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘custom_appearance.Rmd’

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

Quitting from lines 376-378 [unnamed-chunk-10] (example_analysis_coxreg.Rmd)
Error: processing vignette 'example_analysis_coxreg.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘example_analysis_coxreg.Rmd’

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

Quitting from lines 55-57 [unnamed-chunk-5] (exploratory_analysis.Rmd)
Error: processing vignette 'exploratory_analysis.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘exploratory_analysis.Rmd’

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

Quitting from lines 73-81 [unnamed-chunk-4] (format_precedence.Rmd)
Error: processing vignette 'format_precedence.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘format_precedence.Rmd’

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

Quitting from lines 91-102 [unnamed-chunk-4] (introduction.Rmd)
Error: processing vignette 'introduction.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘introduction.Rmd’

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

Quitting from lines 30-40 [unnamed-chunk-3] (introspecting_tables.Rmd)
Error: processing vignette 'introspecting_tables.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘introspecting_tables.Rmd’

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

Quitting from lines 65-66 [unnamed-chunk-5] (manual_table_construction.Rmd)
Error: processing vignette 'manual_table_construction.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘manual_table_construction.Rmd’

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

Quitting from lines 37-51 [unnamed-chunk-3] (sorting_pruning.Rmd)
Error: processing vignette 'sorting_pruning.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘sorting_pruning.Rmd’

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

Quitting from lines 118-127 [examples] (split_functions.Rmd)
Error: processing vignette 'split_functions.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘split_functions.Rmd’

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

Quitting from lines 39-49 [unnamed-chunk-3] (subsetting_tables.Rmd)
Error: processing vignette 'subsetting_tables.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘subsetting_tables.Rmd’

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

Quitting from lines 90-102 [unnamed-chunk-6] (tabulation_concepts.Rmd)
Error: processing vignette 'tabulation_concepts.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘tabulation_concepts.Rmd’

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

Quitting from lines 45-70 [unnamed-chunk-4] (tabulation_dplyr.Rmd)
Error: processing vignette 'tabulation_dplyr.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘tabulation_dplyr.Rmd’

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

Quitting from lines 46-61 [unnamed-chunk-3] (title_footer.Rmd)
Error: processing vignette 'title_footer.Rmd' failed with diagnostics:
argument "fontspec" is missing, with no default
--- failed re-building ‘title_footer.Rmd’

SUMMARY: processing the following files failed:
  ‘advanced_usage.Rmd’ ‘baseline.Rmd’ ‘clinical_trials.Rmd’
  ‘custom_appearance.Rmd’ ‘example_analysis_coxreg.Rmd’
  ‘exploratory_analysis.Rmd’ ‘format_precedence.Rmd’ ‘introduction.Rmd’
  ‘introspecting_tables.Rmd’ ‘manual_table_construction.Rmd’
  ‘sorting_pruning.Rmd’ ‘split_functions.Rmd’ ‘subsetting_tables.Rmd’
  ‘tabulation_concepts.Rmd’ ‘tabulation_dplyr.Rmd’ ‘title_footer.Rmd’

Error: Vignette re-building failed.
Execution halted