Fix gcc12 warnings

I'm getting a few weird warnings when building Gaudi in optimized mode with gcc 12:

• maybe-uninitialized when passing an r-value reference to to std::make_unique (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107138#c4)
• dangling-pointer to an object on the stack of which I'm never trying to access the address

For the first case I decided to hide the warning (432b2972) and for the second I refactored slightly the code (de9ab00c).