fix: no results with configuration citation reference index switched off

- urlcitationindex != null check added to ResultEntry.referencesCount
- plus other places where conflicting procedure was used (and urlcitationindex not already checked != null)

htroot/api/webstructure.java

@@ -142,7 +142,7 @@ public class webstructure {
             	ReferenceContainer<CitationReference> citations = null;
             	// citationReferences.count(urlhash) would give to the number of references good for ranking
                 try {
-					citations = citationReferences.get(urlhash, null);
+                    citations = citationReferences != null ? citationReferences.get(urlhash, null) : null;
                 } catch (IOException e) {
                 }
             	if (citations != null) {

htroot/api/yacydoc.java

@@ -126,7 +126,7 @@ public class yacydoc {
         prop.putXML("yacy_referrer_url", (le == null) ? "" : le.url().toNormalform(true));
         prop.put("yacy_size", entry.size());
         prop.put("yacy_words", entry.wordCount());
-        prop.put("yacy_citations", sb.index.urlCitation().count(entry.hash()));
+        prop.put("yacy_citations", sb.index.urlCitation()!= null ? sb.index.urlCitation().count(entry.hash()) : 0);
         prop.put("yacy_inbound", entry.llocal());
         prop.put("yacy_outbound", entry.lother());
 

source/net/yacy/search/snippet/ResultEntry.java

@@ -163,7 +163,8 @@ public class ResultEntry implements Comparable<ResultEntry>, Comparator<ResultEn
         return this.urlentry.size();
     }
     public int referencesCount() {
-    	return this.indexSegment.urlCitation().count(this.urlentry.hash());
+        // urlCitationIndex index might be null (= configuration option)
+    	return this.indexSegment.urlCitation() != null ? this.indexSegment.urlCitation().count(this.urlentry.hash()) : 0;
     }
     public int llocal() {
     	return this.urlentry.llocal();