REST: Avoid Lucene crashes when searching for 0 documents

libresonic-main/src/main/java/org/libresonic/player/service/SearchService.java

@@ -159,6 +159,8 @@ public class SearchService {
         int count = criteria.getCount();
         result.setOffset(offset);
 
+        if (count <= 0) return result;
+
         IndexReader reader = null;
         try {
             reader = createIndexReader(indexType);