Issue #20026: Fix the sqlite module to handle correctly invalid isolation level
(wrong type).
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index d89b4c1..59966da 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -152,7 +152,10 @@
         Py_INCREF(isolation_level);
     }
     self->isolation_level = NULL;
-    pysqlite_connection_set_isolation_level(self, isolation_level);
+    if (pysqlite_connection_set_isolation_level(self, isolation_level) < 0) {
+        Py_DECREF(isolation_level);
+        return -1;
+    }
     Py_DECREF(isolation_level);
 
     self->statement_cache = (pysqlite_Cache*)PyObject_CallFunction((PyObject*)&pysqlite_CacheType, "Oi", self, cached_statements);