Hey,
You are right, it looks as though the Editor can’t find the file /Script/TMEditor while loading your TMTest.umap.
Here is some links to documentation on Plugins:
- [Plugins Documentation][1]
- [Plugins Wiki][2]
If you find that you’re not able to get around this plugin issue, I would suggest zipping up your project and providing the link to download it and providing that link through a private message on the forums.
Looking forward to hearing back from you. 
Plugins in Unreal Engine | Unreal Engine 5.1 Documentation
[2]: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums