Error(s) in re-building vignettes:
  ...
--- re-building 'international-mortality-tables-overview.Rmd' using rmarkdown
Quitting from lines 235-237 (international-mortality-tables-overview.Rmd) 
Error: processing vignette 'international-mortality-tables-overview.Rmd' failed with diagnostics:
could not find function "whittaker"
--- failed re-building 'international-mortality-tables-overview.Rmd'

--- re-building 'using-the-mortalityTables-package.Rmd' using rmarkdown

(process:21247): Pango-WARNING **: 16:33:33.115: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.171: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.173: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.174: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.190: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.191: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.193: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.195: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.197: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.198: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.274: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.276: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.278: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.280: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.282: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.285: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.903: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.904: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.906: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.908: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.915: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.917: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.918: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.920: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.923: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:33.924: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.003: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.004: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.006: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.008: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.010: Invalid UTF-8 string passed to pango_layout_set_text()

(process:21247): Pango-WARNING **: 16:33:34.012: Invalid UTF-8 string passed to pango_layout_set_text()
--- finished re-building 'using-the-mortalityTables-package.Rmd'

SUMMARY: processing the following file failed:
  'international-mortality-tables-overview.Rmd'

Error: Vignette re-building failed.
Execution halted