Check that $shapes is not empty before using in key()

src/main/webapp/static/com/atomgraph/linkeddatahub/xsl/bootstrap/2.3.2/resource.xsl

@@ -1062,7 +1062,7 @@ extension-element-prefixes="ixsl"
         <xsl:param name="constructors" as="document-node()?" tunnel="yes"/>
         <xsl:param name="constraints" as="document-node()?" tunnel="yes"/>
         <xsl:param name="shapes" as="document-node()?" tunnel="yes"/>
-        <xsl:param name="type-shapes" select="key('shapes-by-target-class', $forClass, $shapes)" as="element()*"/>
+        <xsl:param name="type-shapes" select="if ($shapes) then key('shapes-by-target-class', $forClass, $shapes) else ()" as="element()*"/>
         <xsl:param name="constructor" as="document-node()?">
             <!-- SHACL shapes take priority over SPIN constructors -->
             <xsl:choose use-when="system-property('xsl:product-name') = 'SAXON'">