Discriminator value could be an integer (TypeError is raised)

src/Query/SqlWalker.php

@@ -384,7 +384,7 @@ private function generateDiscriminatorColumnConditionSQL(array $dqlAliases): str
             $values = [];
 
             if ($class->discriminatorValue !== null) { // discriminators can be 0
-                $values[] = $conn->quote($class->discriminatorValue);
+                $values[] = $conn->quote((string) $class->discriminatorValue);
             }
 
             foreach ($class->subClasses as $subclassName) {