Error(s) in re-building vignettes:
  ...
--- re-building ‘MultistateLH.Rmd’ using knitr
key 'gampe2007population'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'wilmoth2021methods'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'littlerubin2019'
      A bibentry of bibtype ‘Book’ has to specify the field: publisher
key 'dequeljoe2023'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'schererl2021'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
--- finished re-building ‘MultistateLH.Rmd’

--- re-building ‘Piecewise_exponential.Rmd’ using knitr
key 'gampe2007population'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'wilmoth2021methods'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'littlerubin2019'
      A bibentry of bibtype ‘Book’ has to specify the field: publisher
key 'dequeljoe2023'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
key 'schererl2021'
      A bibentry of bibtype ‘TechReport’ has to specify the field: institution
--- finished re-building ‘Piecewise_exponential.Rmd’

--- re-building ‘Tutorial.Rmd’ using knitr

Quitting from Tutorial.Rmd:86-90 [unnamed-chunk-3]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<error/rlang_error>
Error in `open.connection()`:
! cannot open the connection
---
Backtrace:
     ▆
  1. └─HMDHFDplus::getHFDcountries()
  2.   ├─xml2::read_html("https://www.humanfertility.org")
  3.   └─xml2:::read_html.default("https://www.humanfertility.org")
  4.     ├─base::suppressWarnings(...)
  5.     │ └─base::withCallingHandlers(...)
  6.     ├─xml2::read_xml(x, encoding = encoding, ..., as_html = TRUE, options = options)
  7.     └─xml2:::read_xml.character(...)
  8.       └─xml2:::read_xml.connection(...)
  9.         ├─base::open(x, "rb")
 10.         └─base::open.connection(x, "rb")
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Error: processing vignette 'Tutorial.Rmd' failed with diagnostics:
cannot open the connection
--- failed re-building ‘Tutorial.Rmd’

SUMMARY: processing the following file failed:
  ‘Tutorial.Rmd’

Error: Vignette re-building failed.
Execution halted