Don't crash at startup when there are no modules

[bnjbvr]

No description provided.

[Yoric]

Happy to try and work on that. How can I reproduce this issue? Running

$ HOMESERVER=localhost:9999 BOT_USER_ID=@bot:localhost:9999 BOT_PWD=password MATRIX_STORE_PATH=./cache REDB_PATH=./example.db ADMIN_USER_ID=@admin:localhost:9999 cargo run

doesn't seem to cause any error message.

[bnjbvr]

Ah nice, maybe I've accidentally fixed it 😀 Thanks for trying it! Would you be interested in adding some kind of tests? (That might require refactoring the core functions a bit 🤔 and such a refactoring would likely improve the overall architecture)