Validate JSON returned from Wikidata's sparql endpoint, throw an

exception if it is invalid

src/NodaWikidataFetcher.php

@@ -436,6 +436,10 @@ final class NodaWikidataFetcher {
         $url = 'https://query.wikidata.org/sparql?query=' . urlencode($sparqlQuery);
         $result = MD_STD::runCurl($url, 100000000, self::WIKIDATA_FETCH_HEADERS);
 
+        if (json_validate($result) === false) {
+            throw new MDhttpFailedException("Failed to run SPARQL query");
+        }
+
         return json_decode($result, true);
 
     }