Guided conversation graph does not seem to save new nodes

The user should be able to add nodes to a guided conversation graph. When a user attempts to add a node, Delvin gives no feedback about whether a node is saved or not. Navigating away and returning to the page shows that the node is not added.

Steps to Reproduce

1. Log in
2. Create a new workspace.
3. Create a new project.
4. Enter project.
5. Click Add Assistant
6. Fill out the bot with default values. For model select on OpenAI key and "GPT-40 mini".
7. Click Next (to create the bot)
8. Click on the newly created bot.
9. Click Open in Flow Editor
10. Click +.
11. Add a new message node.
12. Connect Start to the message node you created.
13. Click Save.