Because I have a lot of trouble with some nondeterministic calls from inside my project's goal,
how can I declare and have my goal to be a (non-)determ instead of a procedure, as it is declared
now (and I don't know where it is declared as such)?
If I don't have procedure type on my goal the VP8 compiler gives me a related error:
e504 The expression has type '() nondeterm', which is incompatible with the type '() procedure' main.pro
You cannot. The goal must be a procedure. The typical goal in a console program contains a call to console::runUtf8 (as in your code). And predicate you provide as argument in that call must also be a procedure.
So in your code main::testtop must be a procedure.
This is very natural, because the goal is what the program run and a program does not "fail" or return many times.
I suggest you read and follow the tutorials and write "small" code until you are comfortable with things like procedure, determ, nondeterm, backtracking, fail, succeed, cut, ...