Fix T39331: Dissolve vertex crash

source/blender/bmesh/intern/bmesh_mods.c

@@ -205,14 +205,16 @@ bool BM_disk_dissolve(BMesh *bm, BMVert *v)
 			return false;
 		}
 		
-		/* get remaining two faces */
-		f = e->l->f;
-		f2 = e->l->radial_next->f;
-
-		if (f != f2) {
-			/* join two remaining faces */
-			if (!BM_faces_join_pair(bm, f, f2, e, true)) {
-				return false;
+		if (e->l) {
+			/* get remaining two faces */
+			f = e->l->f;
+			f2 = e->l->radial_next->f;
+
+			if (f != f2) {
+				/* join two remaining faces */
+				if (!BM_faces_join_pair(bm, f, f2, e, true)) {
+					return false;
+				}
 			}
 		}
 	}