I don't remember to ever have seen such an error message.

You should describe exactly the steps you took, from the very beginning, from even before you opened the editor the first time, if you unpacked any .pak files and where you unpacked them, if you copied any or all unpacked files to the game's Data directory, etc.
Then also if and how you created your own mod. If you made it dependent on Main or only on Shared, etc.

All I could think of is that you are editing stuff inside the Main campaign instead of a mod which the editor rejects afterwards because it's a read-only campaign.

As a side note: it has been described numerous times here in the forum how to set up editor and how to create a mod that modifies the Main campaign.

As a second side note: the editor is all but bug free or easy to use. There is a sticky thread EE Editor Problems/Bugs thread, which you should read.