"smart" formatting yields a "cannot open the connection" error

[bearloga]

Running in format = "simple" mode, we get the following:

sparql_query <- "SELECT DISTINCT
  ?softwareVersion ?publicationDate
WHERE {
  BIND(wd:Q206904 AS ?R)
  ?R p:P348 [
  ps:P348 ?softwareVersion;
  pq:P577 ?publicationDate
  ] .
}"

str(results <- WikidataQueryServiceR::query_wikidata(sparql_query))

'data.frame':	21 obs. of  2 variables:
 $ softwareVersion: chr  "3.3.3" "3.1.0" "3.1.2" "3.2.5" ...
 $ publicationDate: chr  "2017-03-06T00:00:00Z" "2014-04-10T00:00:00Z" "2014-10-31T00:00:00Z" "2016-04-14T00:00:00Z" ...

Using the format = "smart" mode, we'd be able to get a data.frame with publicationDate formatted to POSIXlt:

results <- WikidataQueryServiceR::query_wikidata(sparql_query, format = "smart")

But we get an error instead:

Error in open.connection(con, "rb") : cannot open the connection
In addition: Warning message:
In open.connection(con, "rb") : cannot open file '{
  "head" : {
    "vars" : [ "softwareVersion", "publicationDate" ]
  },
  "results" : {
    "bindings" : [ {
      "softwareVersion" : {
        "type" : "literal",
        "value" : "3.3.3"
      },
      "publicationDate" : {
        "datatype" : "http://www.w3.org/2001/XMLSchema#dateTime",
        "type" : "literal",
        "value" : "2017-03-06T00:00:00Z"
      }