Made AND the default operator for advanced search queries so that any missing...

Made AND the default operator for advanced search queries so that any missing parameters don't make the search fail.

module/VuFind/src/VuFind/Search/QueryAdapter.php

@@ -184,16 +184,14 @@ abstract class QueryAdapter
                 if ($lookfor[$i] != '') {
                     // Use default fields if not set
                     $typeArr = $request->get('type' . $groupCount);
-                    $handler = (isset($typeArr[$i]) && !empty($typeArr[$i]))
-                        ? $typeArr[$i] : $defaultHandler;
+                    $handler = !empty($typeArr[$i]) ? $typeArr[$i] : $defaultHandler;
 
                     $opArr = $request->get('op' . $groupCount);
-                    $operator = (isset($opArr[$i]) && !empty($opArr[$i]))
-                        ? $opArr[$i] : null;
+                    $operator = !empty($opArr[$i]) ? $opArr[$i] : null;
 
                     // Add term to this group
                     $boolArr = $request->get('bool' . $groupCount);
-                    $lastBool = isset($boolArr[0]) ? $boolArr[0] : null;
+                    $lastBool = isset($boolArr[0]) ? $boolArr[0] : 'AND';
                     $group[] = new Query($lookfor[$i], $handler, $operator);
                 }
             }
@@ -209,7 +207,7 @@ abstract class QueryAdapter
         }
 
         return (count($groups) > 0)
-            ? new QueryGroup($request->get('join'), $groups)
+            ? new QueryGroup($request->get('join', 'AND'), $groups)
             : new Query();
     }