Reduced Test Case:
```
{|{{Infobox aircraft begin
}}{{Infobox aircraft type|number built=unknown, 300 ordered<ref>{{cite web|title=The Cannon Pioneers}}</ref>}}
|}
```
The following commandline on scandium causes the crasher. The "--pageName" argument is necessary.
```
php bin/parse.php --dump tplsrc --pageName 'SPAD_S.XII' < /tmp/wt
```
See the comments in the body of this phab task for analysis. This bug is present in the JS code as well, just that these assertions aren't present there to be triggered.
--------------------------------------------------------------------
Request URLs:
* /w/rest.php/en.wikipedia.org/v3/page/pagebundle/User%3ARlandmann%2FB-17_Flying_Fortress/887607268
* /w/rest.php/en.wikipedia.org/v3/page/pagebundle/SPAD_S.XII/933888325
* /w/rest.php/sl.wikipedia.org/v3/transform/wikitext/to/pagebundle/RMS_Olympic
Exception Trace:
```
#0 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMDataUtils.php(69): Wikimedia\Assert\Assert::invariant(boolean, string)
#1 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMDataUtils.php(91): Wikimedia\Parsoid\Utils\DOMDataUtils::getNodeData(DOMElement)
#2 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/PP/Handlers/CleanUp.php(164): Wikimedia\Parsoid\Utils\DOMDataUtils::getDataParsoid(DOMElement)
#3 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/DOMPostProcessor.php(471): Wikimedia\Parsoid\Wt2Html\PP\Handlers\CleanUp::cleanupAndSaveDataParsoid(array, DOMElement, Wikimedia\Parsoid\Config\Env, boolean, stdClass)
#4 [internal function]: Wikimedia\Parsoid\Wt2Html\DOMPostProcessor->Wikimedia\Parsoid\Wt2Html\{closure}(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#5 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(77): call_user_func(Closure, DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#6 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(146): Wikimedia\Parsoid\Utils\DOMTraverser->callHandlers(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#7 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#8 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#9 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#10 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#11 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#12 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#13 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#14 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#15 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#16 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#17 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#18 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#19 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, stdClass)
#20 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Utils/DOMTraverser.php(158): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, NULL)
#21 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/DOMPostProcessor.php(145): Wikimedia\Parsoid\Utils\DOMTraverser->traverse(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean, NULL)
#22 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/DOMPostProcessor.php(829): Wikimedia\Parsoid\Wt2Html\DOMPostProcessor->Wikimedia\Parsoid\Wt2Html\{closure}(DOMElement, Wikimedia\Parsoid\Config\Env, array, boolean)
#23 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/DOMPostProcessor.php(886): Wikimedia\Parsoid\Wt2Html\DOMPostProcessor->doPostProcess(DOMDocument)
#24 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/DOMPostProcessor.php(903): Wikimedia\Parsoid\Wt2Html\DOMPostProcessor->process(DOMDocument)
#25 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/ParserPipeline.php(148): Wikimedia\Parsoid\Wt2Html\DOMPostProcessor->processChunkily(string, array)
#26 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/ParserPipeline.php(198): Wikimedia\Parsoid\Wt2Html\ParserPipeline->parseChunkily(string, array)
#27 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Wt2Html/ParserPipelineFactory.php(290): Wikimedia\Parsoid\Wt2Html\ParserPipeline->parseToplevelDoc(string, array)
#28 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Core/WikitextContentModelHandler.php(78): Wikimedia\Parsoid\Wt2Html\ParserPipelineFactory->parse(string)
#29 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Parsoid.php(148): Wikimedia\Parsoid\Core\WikitextContentModelHandler->toDOM(Wikimedia\Parsoid\Config\Env)
#30 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/src/Parsoid.php(180): Wikimedia\Parsoid\Parsoid->parseWikitext(MWParsoid\Config\PageConfig, array)
#31 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/extension/src/Rest/Handler/ParsoidHandler.php(529): Wikimedia\Parsoid\Parsoid->wikitext2html(MWParsoid\Config\PageConfig, array, NULL)
#32 /srv/mediawiki/php-1.35.0-wmf.26/vendor/wikimedia/parsoid/extension/src/Rest/Handler/PageHandler.php(66): MWParsoid\Rest\Handler\ParsoidHandler->wt2html(MWParsoid\Config\PageConfig, array)
#33 /srv/mediawiki/php-1.35.0-wmf.26/includes/Rest/Router.php(353): MWParsoid\Rest\Handler\PageHandler->execute()
#34 /srv/mediawiki/php-1.35.0-wmf.26/includes/Rest/Router.php(308): MediaWiki\Rest\Router->executeHandler(MWParsoid\Rest\Handler\PageHandler)
#35 /srv/mediawiki/php-1.35.0-wmf.26/includes/Rest/EntryPoint.php(138): MediaWiki\Rest\Router->execute(MediaWiki\Rest\RequestFromGlobals)
#36 /srv/mediawiki/php-1.35.0-wmf.26/includes/Rest/EntryPoint.php(105): MediaWiki\Rest\EntryPoint->execute()
#37 /srv/mediawiki/php-1.35.0-wmf.26/rest.php(31): MediaWiki\Rest\EntryPoint::main()
#38 /srv/mediawiki/w/rest.php(3): require(string)
#39 {main}
```