Hi!

I was reading the game log and noticed this 2 lines:

20.267 Loading mod SmartArtilleryWagons 0.3.0 (data-updates.lua)
20.268 Script @flib/data_util.lua:5: FLIB DEPRECATION WARNING: data_util was renamed to data-util in v0.3.1. Please update your require paths. The old path will cease to work when Factorio 1.1 is released.

If you use FLib, then you should rename the required dependency in your code, because it will otherwise cause errors when 1.1 is released
If you don't, then sorry, I just assumed from the first line that your mod caused this line to be printed