By the way, this neighboring sentence is a bit awkward
" It must be ... or a type for which there is a cast from json to that type."
Would it be better to say
" It must be ... or a type to which a cast from json exists."
?
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Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/
"La espina, desde que nace, ya pincha" (Proverbio africano)