XPATH remove extra spaces in concatenation of elements - xpath

Question

In XPATH, I am treating a source XML that looks like below, where I want to concatenate the child elements of each editor with a space delimiter to create a full name, and then in turn concatenate the resulting full names with commas:
<biblStruct type="book" xml:id="Biller_2011a">
<monogr>
<title>Inquisitors and Heretics in Thirteenth-Century Languedoc: Edition and Translation
of Toulouse Inquisition Depositions, 1273-1282</title>
<editor>
<forename>Peter</forename><surname>Biller</surname>
</editor>
<editor>
<forename>Caterina</forename><surname>Bruschi</surname>
</editor>
<editor>
<forename>Shelagh</forename><surname>Sneddon</surname>
</editor>
<imprint>
<pubPlace>
<settlement>Leiden</settlement>
<country>NL</country>
</pubPlace>
<publisher>Brill</publisher>
<date type="pub_date">2011</date>
</imprint>
</monogr>
</biblStruct>
Currently the XPATH (within XQuery) code looks like this, using XPATH map to introduce delimiters:
let $bibref := $bib//tei:biblStruct[#xml:id="Biller_2011a"]
return <editors>{
(for $auth in $bibref//tei:editor
return normalize-space(string-join($auth//child::text()," ")))!(if (position() > 1) then ', ' else (), .)
}</editors>
But this outputs extra space before and after the commas:
<editors>Peter Biller , Caterina Bruschi , Shelagh Sneddon</editors>
Rather, I want to output:
<editors>Peter Biller, Caterina Bruschi, Shelagh Sneddon</editors>
Thanks in advance.

Answer 1

"where I want to concatenate the child elements of each editor" would translate into $auth/* and not into $auth//child::text().
Somehow the whole mix of for return and ! and string-join looks odd, it seems you can just use string-join($bibref//tei:editor/string-join(*, ' '), ', ').