diff --git a/LeanMapperQuery/Entity.php b/LeanMapperQuery/Entity.php
index fd862ac..0239a09 100644
--- a/LeanMapperQuery/Entity.php
+++ b/LeanMapperQuery/Entity.php
@@ -98,7 +98,9 @@ public static function queryEntityProperty(LeanMapper\Entity $entity, $field, IQ
 				if ($row !== null && $targetResultProxy === null) {
 					$targetResultProxy = $row->getResultProxy();
 				}
-				$row !== null && $resultRows[$row->{$targetPrimaryKey}] = $row;
+				if ($row !== null) {
+					$resultRows[$row->{$targetPrimaryKey}] = $row;
+				}
 			}
 
 			if ($targetResultProxy) {
diff --git a/LeanMapperQuery/Query.php b/LeanMapperQuery/Query.php
index ee0a586..b2db803 100644
--- a/LeanMapperQuery/Query.php
+++ b/LeanMapperQuery/Query.php
@@ -266,7 +266,7 @@ private function traverseToRelatedEntity(&$currentTable, &$currentTableAlias, Pr
 			$targetTableAlias = $this->joinRelatedTable($relationshipTableAlias, $targetReferencingColumn, $targetTable, $targetTablePrimaryKey, $implicitFilters, false);
 
 		} else {
-			throw new InvalidRelationshipException('Unknown relationship type. ' . get_class($relationship) . ' given.');
+			throw new InvalidRelationshipException('Unknown relationship type in property {$property->getName()}.');
 		}
 		$currentTable = $targetTable;
 		$currentTableAlias = $targetTableAlias;
diff --git a/phpstan.neon b/phpstan.neon
index b915a5e..7eed3e4 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,4 +1,4 @@
 parameters:
-	level: 3
+	level: 5
 	paths:
 		- LeanMapperQuery/