Error adding tag after open tag with xmlOutputBuffer

[adfi]

Hi,

I'm getting an error when running the following code:
doc <- xmlOutputBuffer()
doc$addTag("bravo", close=FALSE)
doc$addTag("charlie", "forename")
Error in if (!startingTag && !is.null(namespace) && namespace == nameSpace && :
missing value where TRUE/FALSE needed

This is how xmlOutputBuffer appears in the documentation:
xmlOutputBuffer(dtd=NULL, nameSpace="", buf=NULL, nsURI=NULL, header="<?xml version=\"1.0\"?>")

And this is how it appears in the source code:
xmlOutputBuffer <- function(dtd = NULL, nameSpace = NULL, buf = NULL, nsURI = NULL, header = "<?xml version=\"1.0\"?>") {..}

When calling the function with nameSpace="" the error does not appear.