From 517b8ff1eef6a860e615d690f2cd1f2ba01464fd Mon Sep 17 00:00:00 2001
From: "kr.angelov" <kr.angelov@gmail.com>
Date: Tue, 7 May 2013 08:35:33 +0000
Subject: [PATCH] bugfix for bracketedLinearize which was causing crash if the
 tree cannot be linearized

---
 src/runtime/python/pypgf.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/runtime/python/pypgf.c b/src/runtime/python/pypgf.c
index de5ead10f..1e11edcb5 100644
--- a/src/runtime/python/pypgf.c
+++ b/src/runtime/python/pypgf.c
@@ -1171,8 +1171,14 @@ Concr_bracketedLinearize(ConcrObject* self, PyObject *args)
 
 	gu_pool_free(tmp_pool);
 	
-	PyObject* bracket = PyList_GetItem(list, 0);
-	Py_INCREF(bracket);
+	PyObject* bracket = NULL;
+	if (PyList_Size(list) == 1) {
+		bracket = PyList_GetItem(list, 0);
+		Py_INCREF(bracket);
+	} else {
+		PyErr_SetString(PGFError, "The abstract tree cannot be linearized");
+	}
+
 	Py_DECREF(list);
 
 	return bracket;