Remove optional chaining

..which is unsupported in Node 10

nuts-data.js

@@ -82,7 +82,7 @@ module.exports.loadOntology = async function(filePath) {
 
 module.exports.parseDatasetsMetadata = function(ontology) {
     return ontology
-        .filter((entity) => entity['@type']?.includes('http://www.semanticweb.org/attractiveness/Dataset'))
+        .filter((entity) => entity['@type'] ? entity['@type'].includes('http://www.semanticweb.org/attractiveness/Dataset') : null)
         .filter(
             (entity) => entity['http://www.semanticweb.org/attractiveness/hasCoverage']
                 .some((coverage) => coverage['@id'] == 'http://www.semanticweb.org/attractiveness/Europe')
@@ -95,8 +95,8 @@ module.exports.parseDatasetsMetadata = function(ontology) {
             return {
                 name: entity['@id'].split('/').splice(-1).pop(),
                 //FIXME: instead of [0] search for "@language"="en"
-                description: entity['http://www.semanticweb.org/attractiveness#description']?.[0]['@value'],
-                factor: entity['http://www.semanticweb.org/attractiveness/isDatasetOf']?.[0]['@id'].split('/').splice(-1).pop()
+                description: entity['http://www.semanticweb.org/attractiveness#description'] ? entity['http://www.semanticweb.org/attractiveness#description'][0]['@value'] : '',
+                factor: entity['http://www.semanticweb.org/attractiveness/isDatasetOf'] ? entity['http://www.semanticweb.org/attractiveness/isDatasetOf'][0]['@id'].split('/').splice(-1).pop() : ''
             }
         })
 }