Running examples in 'selectr-Ex.R' failed
The error most likely occurred in:

> ### Name: querySelectorAll
> ### Title: Find nodes that match a group of CSS selectors in an XML tree.
> ### Aliases: querySelector querySelectorAll querySelectorNS
> ###   querySelectorAllNS
> 
> ### ** Examples
> 
>   hasXML <- require(XML)
Loading required package: XML
Warning in library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
  there is no package called 'XML'
>   hasxml2 <- require(xml2)
Loading required package: xml2
> 
>   if (!hasXML && !hasxml2)
+     return() # can't demo without XML or xml2 packages present
> 
>   parseFn <- if (hasXML) xmlParse else read_xml
>   # Demo for working with the XML package (if present, otherwise xml2)
>   exdoc <- parseFn('<a><b class="aclass"/><c id="anid"/></a>')
>   querySelector(exdoc, "#anid")   # Returns the matching node
{xml_node}
<c id="anid">
>   querySelector(exdoc, ".aclass") # Returns the matching node
{xml_node}
<b class="aclass">
>   querySelector(exdoc, "b, c")    # First match from grouped selection
{xml_node}
<b class="aclass">
>   querySelectorAll(exdoc, "b, c") # Grouped selection
{xml_nodeset (2)}
[1] <b class="aclass"/>
[2] <c id="anid"/>
>   querySelectorAll(exdoc, "b")    # A list of length one
{xml_nodeset (1)}
[1] <b class="aclass"/>
>   querySelector(exdoc, "d")       # No match
NULL
>   querySelectorAll(exdoc, "d")    # No match
{xml_nodeset (0)}
> 
>   # Read in a document where two namespaces are being set:
>   # SVG and MathML
>   svgdoc <- parseFn(system.file("demos/svg-mathml.svg",
+                                 package = "selectr"))
>   # Search for <script/> elements in the SVG namespace
>   querySelectorNS(svgdoc, "svg|script",
+                   c(svg = "http://www.w3.org/2000/svg"))
{xml_node}
<script type="application/ecmascript" href="test2.svg.coords.js">
>   querySelectorAllNS(svgdoc, "svg|script",
+                      c(svg = "http://www.w3.org/2000/svg"))
{xml_nodeset (2)}
[1] <script type="application/ecmascript" xlink:href="test2.svg.coords.js"/>
[2] <script type="application/ecmascript" xlink:href="test2.svg.convert.js"/>
>   # MathML content is *within* SVG content,
>   # search for <mtext> elements within the MathML namespace
>   querySelectorNS(svgdoc, "math|mtext",
+                   c(math = "http://www.w3.org/1998/Math/MathML"))
{xml_node}
<mtext mathvariant="sans-serif">
>   querySelectorAllNS(svgdoc, "math|mtext",
+                      c(math = "http://www.w3.org/1998/Math/MathML"))
{xml_nodeset (2)}
[1] <mtext mathvariant="sans-serif">a</mtext>
[2] <mtext mathvariant="sans-serif">b</mtext>
>   # Search for *both* SVG and MathML content
>   querySelectorAllNS(svgdoc, "svg|script, math|mo",
+                      c(svg = "http://www.w3.org/2000/svg",
+                        math = "http://www.w3.org/1998/Math/MathML"))
{xml_nodeset (3)}
[1] <mo>+</mo>
[2] <script type="application/ecmascript" xlink:href="test2.svg.coords.js"/>
[3] <script type="application/ecmascript" xlink:href="test2.svg.convert.js"/>
> 
>   if (!hasXML)
+     return() # already demo'd xml2
Error: no function to return from, jumping to top level
Execution halted