Error(s) in re-building vignettes:
  ...
--- re-building ‘anchored_binary.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘anchored_binary.Rmd’

--- re-building ‘anchored_survival.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘anchored_survival.Rmd’

--- re-building ‘calculating_weights.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
Could not fetch http://www.zotero.org/styles/elsevier-vancouver
HttpExceptionRequest Request {
  host                 = "www.zotero.org"
  port                 = 80
  secure               = False
  requestHeaders       = []
  path                 = "/styles/elsevier-vancouver"
  queryString          = ""
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
  proxySecureMode      = ProxySecureWithConnect
}
 ConnectionTimeout
Error: processing vignette 'calculating_weights.Rmd' failed with diagnostics:
pandoc document conversion failed with error 61
--- failed re-building ‘calculating_weights.Rmd’

--- re-building ‘introduction.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘introduction.Rmd’

--- re-building ‘kaplan_meier_plots.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘kaplan_meier_plots.Rmd’

--- re-building ‘unanchored_binary.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘unanchored_binary.Rmd’

--- re-building ‘unanchored_survival.Rmd’ using rmarkdown
[WARNING] Deprecated: --highlight-style. Use --syntax-highlighting instead.
--- finished re-building ‘unanchored_survival.Rmd’

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

Error: Vignette re-building failed.
Execution halted