Get results with undirected graph but not with multidigraph

Question

Dear people of stackoverflow,

I made a routeplanner based on length and elevation. With both costfactors I get only results with an undirected graph. So the code is good for an undirect graph but doesn't work with a MultiDiGraph as input, which I want because it is necessary with elevation.

The errors I get:

number 1:

~\anaconda3\envs\environmentwithhighestversion\lib\site- 
packages\osmnx\plot.py in 
plot_graph_route(G, route, route_color, route_linewidth, route_alpha, 
orig_dest_size, ax, 
**pg_kwargs)
292 
293     # scatterplot origin and destination points (first/last nodes in 
 route)
 --> 294     x = (G.nodes[route[0]]["x"], G.nodes[route[-1]]["x"])
295     y = (G.nodes[route[0]]["y"], G.nodes[route[-1]]["y"])
296     ax.scatter(x, y, s=orig_dest_size, c=route_color, 
 alpha=route_alpha, edgecolor="none")
 TypeError: 'NoneType' object is not subscriptable

Number 2:

~\anaconda3\envs\environmentwithhighestversion\lib\site- 
packages\osmnx\utils_graph.py in get_route_edge_attributes(G, route, 
attribute, minimize_key, retrieve_default)
263     """
264     attribute_values = []
--> 265     for u, v in zip(route[:-1], route[1:]):
266         # if there are parallel edges between two nodes, select the 
one with the
267         # lowest value of minimize_key
TypeError: 'NoneType' object is not subscriptable

The code is partly altered, the original code is of G. Boeing (2021): https://github.com/gboeing/osmnx-examples/blob/main/notebooks/12-node-elevations-edge-grades.ipynb Here is also a reproducible example possible.

The code for the first error:

---

TypeError                                 Traceback (most recent call 
last)
<ipython-input-3-86e03594e5bd> in <module>
  7 route_by_impedance = ox.shortest_path(G7, source, target, 
weight="impedance")
  8 print('Route Impedance:')
----> 9 fig, ax = ox.plot_graph_route(G7, route_by_impedance, 
 node_size=3)
 10 def print_route_stats(route):
 11     route_grades = ox.utils_graph.get_route_edge_attributes(G7, 
 route, "grade_abs")

The code for the second error:

ipython-input-4-4eb87f73e021> in print_route_stats(route)
  9 #fig, ax = ox.plot_graph_route(G7, route_by_impedance, node_size=3)
 10 def print_route_stats(route):
 ---> 11     route_grades = ox.utils_graph.get_route_edge_attributes(G7, 
route, "grade_abs")
 12     msg = "The average grade is {:.1f}% and the max is {:.1f}%"
 13     print(msg.format(np.mean(route_grades) * 100, 
np.max(route_grades) * 100))

Does anybody know why I get this problem?

Kind regards,

Damiaan