"NAs introduced by coercion" when running checkForServer()

[daattali]

In the checkForServer() function, there is a line

selJAR <- xpathSApply(selXML, "//s:Key[contains(text(),'selenium-server-standalone')]", 
                       namespaces = c(s = "http://doc.s3.amazonaws.com/2006-03-01"), 
                       xmlValue)

that returns a list of the different versions of the jar file. The next line has

as.numeric(gsub("(.*)/.*", "\\1", selJAR))

Which assumes the list returned earlier was completely numeric. But the latest version has the string "beta" in it, so the conversion to numeric throws a warning.

> tail(gsub("(.*)/.*", "\\1", selJAR))
[1] "2.50"      "2.51"      "2.52"      "2.53"      "2.53"      "3.0-beta1"