fix https://trac.osgeo.org/grass/changeset/51022

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@51024 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/vector/Vlib/read_pg.c

@@ -732,7 +732,8 @@ SF_FeatureType cache_feature(const char *data, int skip_polygon,
 	reallocate_cache(cache, 1);
     }
     cache->lines_num = 0;
-    fparts->n_parts = 0;
+    if (fparts)
+	fparts->n_parts = 0;
     
     ret = -1;
     if (ftype == SF_POINT) {