Can't find file '/Script/OldProject' after migrating to NewProject?

I migrated a single actor blueprint and all of its dependencies to a new blank project of the same project version.
I had a C++ Blueprint Library written for a dialog system. I copied both the .cpp and .h file (a single class) to my new project’s Source folder manually. There, I replaced the class definition in the header: Before, it was class


I changed it to NEWPROJECT_API UDialogFileLoader. I also replaced the header file in the .cpp file to match my new project. I compiled and it worked. However, when I packaged the game, the following line could be found:

Warning: Can’t find file ‘/Script/OldProject’, which was weird, because I couldn’t find any references to my OldProject at all, in no build file, in no class file etc.
Since I’m not that experienced with packaging, I’d like to know a) what is this Script folder and where can I find it? I couldn’t find it at all, neither in my project folder nor in the engine folder. And b) how can I fix this?