Thick mode defers throwing the exception until a fetch is attempted.

tests/test_4300_cursor_other.py

@@ -986,6 +986,7 @@ def test_4366(self):
             from dual"""
         with self.assertRaisesFullCode("ORA-01476"):
             self.cursor.execute(sql, val="a")
+            self.cursor.fetchall()
         self.cursor.execute(sql, val="bb")
         lob, num_val = self.cursor.fetchone()
         self.assertEqual(lob.read(), "bb")