ld+json is invalid: provided as string rather than JSON object

[pkern]

Looking at the bottom of https://manpages.debian.org/trixie/manpages-dev/getloadavg.3.en.html I see this:

<script type="application/ld+json">
"{\"@context\":\"http://schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"item\":{\"@type\":\"Thing\",\"@id\":\"/contents-trixie.html\",\"name\":\"trixie\"}},{\"@type\":\"ListItem\",\"position\":2,\"item\":{\"@type\":\"Thing\",\"@id\":\"/trixie/manpages-dev/index.html\",\"name\":\"manpages-dev\"}},{\"@type\":\"ListItem\",\"position\":3,\"item\":{\"@type\":\"Thing\",\"@id\":\"\",\"name\":\"getloadavg(3)\"}}]}"
</script>

The JSON object gets wrapped into another string, which makes it invalid per the spec. (And Google can't parse it, which is how I found this.)