From 5a54596fe8790cb7596c6c1bad32b3f62e12b4ab Mon Sep 17 00:00:00 2001
From: "kr.angelov" <kr.angelov@gmail.com>
Date: Tue, 19 Feb 2013 12:08:48 +0000
Subject: [PATCH] the parser in the C runtime should not crash if the start
 category is not defined

---
 src/runtime/c/pgf/parser.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/runtime/c/pgf/parser.c b/src/runtime/c/pgf/parser.c
index 80de54ce8..092abb917 100644
--- a/src/runtime/c/pgf/parser.c
+++ b/src/runtime/c/pgf/parser.c
@@ -1976,10 +1976,9 @@ pgf_parser_init_state(PgfConcr* concr, PgfCId cat, size_t lin_idx, GuPool* pool)
 {
 	PgfCncCat* cnccat =
 		gu_map_get(concr->cnccats, &cat, PgfCncCat*);
-	if (!cnccat) {
-		// error ...
-		gu_impossible();
-	}
+	if (!cnccat)
+		return NULL;
+
 	gu_assert(lin_idx < cnccat->n_lins);
 
 	PgfParsing* ps =