I runned git grep -n ChainedTextFrame and just found these:
odk/docs/idl/idl_chapter_refs.txt:6061:com.sun.star.text.ChainedTextFrame
offapi/UnoApi_offapi.mk:1342:   ChainedTextFrame \
offapi/com/sun/star/text/ChainedTextFrame.idl:26:    with other ChainedTextFrame instances that will make the text
offapi/com/sun/star/text/ChainedTextFrame.idl:30:published service ChainedTextFrame
offapi/type_reference/offapi.idl:14058:    published service ChainedTextFrame {
offapi/type_reference/typelibrary_history.txt:45:  adjust ChainedTextFrame service. Remove XChainable interface and insert properties.

Noel: I'm not sure but it seems this class has never been implemented. If yes, perhaps we should just remove it?
I hesitate a bit because when looking at offapi/com/sun/star/text/ChainedTextFrame.idl, there are "ChainNextName" and "ChainPrevName"
(see https://opengrok.libreoffice.org/xref/core/offapi/com/sun/star/text/ChainedTextFrame.idl?r=5687eba4)
and when git grepping, I got:

git grep -n ChainNextName
include/editeng/unoprnms.hxx:126:inline constexpr OUStringLiteral UNO_NAME_TEXT_CHAINNEXTNAME = u"TextChainNextName";
offapi/com/sun/star/text/ChainedTextFrame.idl:38:    [property, maybevoid] string ChainNextName;
offapi/type_reference/offapi.idl:14060:     [property, maybevoid] string ChainNextName;
sw/inc/unoprnms.hxx:249:inline constexpr OUStringLiteral UNO_NAME_CHAIN_NEXT_NAME = u"ChainNextName";
sw/qa/extras/odfimport/odfimport.cxx:679:            getProperty<OUString>(xFrame1, "ChainNextName"));
sw/qa/extras/odfimport/odfimport.cxx:683:            getProperty<OUString>(xFrame2, "ChainNextName"));
sw/qa/extras/ooxmlexport/ooxmlexport17.cxx:921:        xTextBox1Properties->getPropertyValue("ChainNextName").get<OUString>());
sw/source/filter/ww8/wrtw8nds.cxx:671:            if( xPropertySetInfo->hasPropertyByName("ChainNextName") )
sw/source/filter/ww8/wrtw8nds.cxx:672:                xPropertySet->getPropertyValue("ChainNextName") >>= aLinkedTextboxInfo.sNextChain;
writerfilter/source/dmapper/DomainMapper_Impl.cxx:4909:        OUString sChainNextName("ChainNextName");
writerfilter/source/dmapper/DomainMapper_Impl.cxx:4999:                    xPropertySet->setPropertyValue(sChainNextName, uno::Any(nextFinder->second.shapeName));
writerfilter/source/dmapper/DomainMapper_Impl.cxx:5024:                            xPropertySet->setPropertyValue(sChainNextName, uno::Any(rInner.shapeName));
xmloff/inc/xmlprop.hxx:611:inline constexpr OUStringLiteral PROP_TextChainNextName = u"TextChainNextName";
xmloff/source/draw/sdpropls.cxx:152:    GMAP( PROP_TextChainNextName,              XML_NAMESPACE_DRAW,   XML_CHAIN_NEXT_NAME,      XML_TYPE_STRING, 0 ),
xmloff/source/draw/ximpshap.cxx:1488:    maChainNextName("")
xmloff/source/draw/ximpshap.cxx:1506:            maChainNextName = aIter.toString();
xmloff/source/draw/ximpshap.cxx:1643:    if(!maChainNextName.isEmpty())
xmloff/source/draw/ximpshap.cxx:1650:                xPropSet->setPropertyValue("TextChainNextName",
xmloff/source/draw/ximpshap.cxx:1651:                                           uno::Any( maChainNextName ) );
xmloff/source/draw/ximpshap.hxx:239:    OUString                    maChainNextName;
xmloff/source/text/txtimp.cxx:2183:            rFrmPropSet->setPropertyValue("ChainNextName",
xmloff/source/text/txtparae.cxx:135:constexpr OUStringLiteral gsChainNextName(u"ChainNextName");
xmloff/source/text/txtparae.cxx:3174:    if( rPropSetInfo->hasPropertyByName( gsChainNextName ) )
xmloff/source/text/txtparae.cxx:3177:        if( (rPropSet->getPropertyValue( gsChainNextName ) >>= sNext) && !sNext.isEmpty() )


git grep -n ChainPrevName
offapi/com/sun/star/text/ChainedTextFrame.idl:44:    [property, maybevoid] string ChainPrevName;
offapi/type_reference/offapi.idl:14061:     [property, maybevoid] string ChainPrevName;
sw/inc/unoprnms.hxx:250:inline constexpr OUStringLiteral UNO_NAME_CHAIN_PREV_NAME = u"ChainPrevName";
sw/qa/extras/odfimport/odfimport.cxx:677:            getProperty<OUString>(xFrame1, "ChainPrevName"));
sw/qa/extras/odfimport/odfimport.cxx:681:            getProperty<OUString>(xFrame2, "ChainPrevName"));
sw/qa/extras/ooxmlexport/ooxmlexport17.cxx:924:        xTextBox2Properties->getPropertyValue("ChainPrevName").get<OUString>());
sw/source/filter/ww8/wrtw8nds.cxx:673:            if( xPropertySetInfo->hasPropertyByName("ChainPrevName") )
sw/source/filter/ww8/wrtw8nds.cxx:674:                xPropertySet->getPropertyValue("ChainPrevName") >>= aLinkedTextboxInfo.sPrevChain;
xmloff/source/text/txtimp.cxx:2206:            rFrmPropSet->setPropertyValue("ChainPrevName", Any(*i));

Yeah, this service has never been implemented, feel free to remove it

(In reply to Noel Grandin from comment #2)
> Yeah, this service has never been implemented, feel free to remove it

Thank you for the feedback, I gave a try with https://gerrit.libreoffice.org/c/core/+/147743.
Locally it built on pc Debian x86-64 with master sources updated today.
(I didn't do a "make clean" for a test from scratch)

My patch is wrong, I'll let this one for others.
Sorry for the noise Noel.