fix: get_dag时matin matout为空时不报错

apps/mtm/models.py

@@ -485,6 +485,7 @@ class Route(CommonADModel):
         edges = []
 
         for rq in rqs:
+            if rq.material_in and rq.material_out:
                 source = rq.material_in.id
                 target = rq.material_out.id
                 nodes_set.update([source, target])