Backtick as key in json cause error with DataFrames

[mario-arduini]

When using DataFrame operations with structured-json-file and a key contains a backtick ` it leads to an error.

difficult-names.json: (note the last key)
{"1": "one", "include spaces": "impressive", "quotes"": "very tricky", "keyToUse" : "1", "backtick" : "oh cmon"} {"1": "two", "include spaces": "amazing", "quotes\"": "unexpected", "keyToUse" : "include spaces", "backtick" : "why?"}

query:
for $i in structured-json-file("difficult-names.json")
let $c := $i."backtick`"
return $c

Expected result:
oh cmon
why

Got:
[ERROR] An error has occurred:
extraneous input 'spaces' expecting {')', ','}(line 1, pos 39)

== SQL ==
SELECT struct(1,backtick``,include spaces,keyToUse,quotes") AS i` FROM assignment
---------------------------------------^^^