Error(s) in re-building vignettes:
--- re-building 'charitable.Rmd' using rmarkdown
Could not fetch https://polyfill.io/v3/polyfill.min.js?features=es6
HttpExceptionRequest Request {
  host                 = "polyfill.io"
  port                 = 443
  secure               = True
  requestHeaders       = []
  path                 = "/v3/polyfill.min.js"
  queryString          = "?features=es6"
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (InternalException (HandshakeFailed (Error_Misc "Network.Socket.recvBuf: invalid argument (Invalid argument)")))
Error: processing vignette 'charitable.Rmd' failed with diagnostics:
pandoc document conversion failed with error 61
--- failed re-building 'charitable.Rmd'

--- re-building 'escount.Rmd' using rmarkdown
Could not fetch https://polyfill.io/v3/polyfill.min.js?features=es6
HttpExceptionRequest Request {
  host                 = "polyfill.io"
  port                 = 443
  secure               = True
  requestHeaders       = []
  path                 = "/v3/polyfill.min.js"
  queryString          = "?features=es6"
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (InternalException (HandshakeFailed (Error_Misc "Network.Socket.recvBuf: invalid argument (Invalid argument)")))
Error: processing vignette 'escount.Rmd' failed with diagnostics:
pandoc document conversion failed with error 61
--- failed re-building 'escount.Rmd'

--- re-building 'expreg.Rmd' using rmarkdown
Could not fetch https://polyfill.io/v3/polyfill.min.js?features=es6
HttpExceptionRequest Request {
  host                 = "polyfill.io"
  port                 = 443
  secure               = True
  requestHeaders       = []
  path                 = "/v3/polyfill.min.js"
  queryString          = "?features=es6"
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (InternalException (HandshakeFailed (Error_Misc "Network.Socket.recvBuf: invalid argument (Invalid argument)")))
Error: processing vignette 'expreg.Rmd' failed with diagnostics:
pandoc document conversion failed with error 61
--- failed re-building 'expreg.Rmd'

--- re-building 'ndvuong.Rmd' using rmarkdown
[WARNING] Citeproc: citation BHAT:95 not found
[WARNING] Citeproc: citation CROI:20 not found
[WARNING] Citeproc: citation KOPP:WEN:00 not found
[WARNING] Citeproc: citation LEON:MIGU:17 not found
[WARNING] Citeproc: citation WEN:KOPP:01 not found
Could not fetch https://polyfill.io/v3/polyfill.min.js?features=es6
HttpExceptionRequest Request {
  host                 = "polyfill.io"
  port                 = 443
  secure               = True
  requestHeaders       = []
  path                 = "/v3/polyfill.min.js"
  queryString          = "?features=es6"
  method               = "GET"
  proxy                = Nothing
  rawBody              = False
  redirectCount        = 10
  responseTimeout      = ResponseTimeoutDefault
  requestVersion       = HTTP/1.1
}
 (InternalException (HandshakeFailed (Error_Misc "Network.Socket.recvBuf: invalid argument (Invalid argument)")))
Error: processing vignette 'ndvuong.Rmd' failed with diagnostics:
pandoc document conversion failed with error 61
--- failed re-building 'ndvuong.Rmd'

SUMMARY: processing the following files failed:
  'charitable.Rmd' 'escount.Rmd' 'expreg.Rmd' 'ndvuong.Rmd'

Error: Vignette re-building failed.
Execution halted