check if response from uri.gbv.de actually contain data before using it and fall back to data from ws.gbv.de if not

Author: Arraverz

src/updater/gndUpdater.js

@@ -99,7 +99,7 @@ main = (payload) => {
             let requests = [];
 
             URIList.forEach((uri) => {
-                if(uri) {
+                if (uri) {
                     var gndURIParts = uri.split('/');
                     let gndID = gndURIParts.pop();
                     let dataRequestUrl = `https://uri.gbv.de/terminology/entityfacts/${gndID}?format=json`
@@ -126,7 +126,11 @@ main = (payload) => {
                         error: null
                     };
                     if (response.ok) {
-                        result.data = response.json();
+                        if (response.headers.get('content-length') === '0') {
+                            result.data = null
+                        } else {
+                            result.data = response.json();
+                        }
                     } else {
                         result.error = "Error fetching data from " + url + ": " + response.status + " " + response.statusText;
                     }

src/webfrontend/CustomDataTypeGND.coffee

@@ -317,6 +317,8 @@ class CustomDataTypeGND extends CustomDataTypeWithCommonsAsPlugin
               .done((data, status, statusText) ->
                 # note: subjectheadings and works are not part of entityfacts yet
                 # --> data will be empty, which is handled by falling back to cdata-defaults from autocomplete
+                if !data
+                  data = {}
 
                 pluginConfig = ez5.session.getBaseConfig("plugin", "custom-data-type-gnd")
 

src/webfrontend/GNDUtil.coffee

@@ -57,7 +57,7 @@ class GNDUtil
 
     # changed: lobid used 'id', entityfacts uses '@id'
     if fulltextConfig?.id
-      if efJSON['@id'] and 
+      if efJSON['@id'] 
         _fulltext += efJSON['@id'] + ' '
       else
         _fulltext += cdata.conceptURI + ' '