conditional loop in XSLT

I have a sample XML which have to loop 3 times to get output. But sometime, one of the loop (attrQualMany name="pagecontain") can be optional, which is creating problem here.

The sample XML is

<document>
<item>
<ID>1000909090</ID>
<flex>
    <attrGroupMany name="pageinfo">
        <row>
            <attrQualMany name="pageinput">
                <value qual="en">User Intake</value>
            </attrQualMany>
            <attrGroupMany name="pagetype">   <!-- Mandatory Loop -->
                <row>
                    <attr name="pagemeasure">EXACT</attr> 
                    <attrQualMany name="pagecontain">  <!-- Optional Loop -->
                        <value qual="GR1">20</value>
                        <value qual="GR2">21</value>
                    </attrQualMany>
                </row>
                <row>
                    <attr name="pagemeasure">EXACT</attr> 
                    <attrQualMany name="pagecontain"><!-- Optional Loop -->
                        <value qual="JH1">30</value>
                        <value qual="JH2">31</value>
                    </attrQualMany>
                </row>
            </attrGroupMany>
            <attr name="pagestate">PREPARED</attr>
            <attrQualMany name="pagewidth">  <!-- Mandatory Loop -->
                <value qual="OZ">10</value>
                <value qual="AB">11</value>
            </attrQualMany>
        </row>
    </attrGroupMany>
</flex>
</item>
</document>

I am using below XSLT which is working fine when we have all the loops present.

XSLT

<xsl:stylesheet xmlns:xsl="http://ift.tt/tCZ8VR" version="1.0">
<xsl:output method="xml" indent="yes" />
<xsl:template match="/document">
    <CatalogItem>
        <RelationshipData>
            <Relationship>
                <RelationType>PAGEDETAILSINFO</RelationType>
                <xsl:variable name="pagetype" select="//attrGroupMany[@name = 'pagetype']/row"/>
                <xsl:variable name="pagecontain" select="$pagetype//attrQualMany[@name='pagecontain']"/>
                <xsl:variable name="pagewidth" select="//attrQualMany[@name = 'pagewidth']/value"/>
                <RelatedItems count="{count($pagetype) * count($pagecontain) * count($pagewidth)}">
                    <xsl:for-each select="$pagetype">
                        <xsl:variable name="attr" select="attr[@name='pagemeasure']"/>
                        <xsl:for-each select=".//attrQualMany[@name='pagecontain']/value">
                            <xsl:variable name="value" select="."/>
                            <xsl:variable name="value1" select="./@qual"/>
                            <xsl:for-each select="$pagewidth">
                                <RelatedItem referenceKey="{concat('PAGEDETAILSINFO','-',ancestor::item/ID,'-',../../attr[@name='pagestate'], '-', . ,'-', @qual, '-', $attr , '-',$value, '-', $value1)}"/>
                            </xsl:for-each>
                        </xsl:for-each>
                    </xsl:for-each>
                </RelatedItems>
            </Relationship>
        </RelationshipData>
    </CatalogItem>
</xsl:template>
</xsl:stylesheet>

If the XML is not having optional loop and looks like below, it is not returning any value

<document>
<item>
<ID>1000909090</ID>
<flex>
    <attrGroupMany name="pageinfo">
        <row>
            <attrQualMany name="pageinput">
                <value qual="en">User Intake</value>
            </attrQualMany>
            <attrGroupMany name="pagetype">
                <row>
                    <attr name="pagemeasure">EXACT</attr>
                </row>
                <row>
                    <attr name="pagemeasure">EXACT</attr>
                </row>
            </attrGroupMany>
            <attr name="pagestate">PREPARED</attr>
            <attrQualMany name="pagewidth">
                <value qual="OZ">10</value>
                <value qual="AB">11</value>
            </attrQualMany>
        </row>
    </attrGroupMany>
</flex>
</item>
</document>