From ac991dc6cd7944e097df04da327ab82239a50ad1 Mon Sep 17 00:00:00 2001
From: Razin Shaikh <razinshaikh@outlook.com>
Date: Thu, 1 Aug 2024 19:03:35 +0100
Subject: [PATCH] if there are no edges, then raise an error

---
 pyzx/graph/multigraph.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pyzx/graph/multigraph.py b/pyzx/graph/multigraph.py
index 932ad93f..37e14817 100644
--- a/pyzx/graph/multigraph.py
+++ b/pyzx/graph/multigraph.py
@@ -336,6 +336,8 @@ def connected(self,v1,v2):
     def edge_type(self, e):
         if len(e) == 2:
             edges = list(self.edges(e[0],e[1]))
+            if len(edges) == 0:
+                raise ValueError('Edge not found')
             if len(edges) > 1:
                 # if all edges are of the same type, return that type
                 if all(e[2] == edges[0][2] for e in edges):