Why doesn't gulp want to execute tasks synchronously?

Question

JavaScript

I am building a frontend application for myself for convenience. In general, everything works except for the detail that it is impossible to start the tasks strictly one by one.
I divided the assembly into environments and the prod environment takes some files from the dev environment, and I want to make a general task so that the whole thing is assembled. Therefore, it is necessary to run dev strictly before prod.
Used several methods, all do not work.
Here is an implementation example:
https://github.com/nepster-web/frontend-box/blob/m...
Please tell me what could be the problem.
P.S. individually everything works.