validate_dem_params.RdHelper function for validating that all required demographic parameter matrices have been defined and that they are all of the correct dimension.
validate_dem_params(dem_params, model_dims)a named list containing the demographic rate matrices. List elements must have the same names as stated above.
a named list containing expected model dimensions. List element must be: nyears, nages, nsexes, nregions, and nfleets.
unmodified dem_params object; if dem_params list is invalid, will return a descriptive error message
Required demographic parameters are: mort, waa, sexrat, sel, ret, dmr, and surv_sel
Expected dimensions are: [nyears, nages, nsexes, nregions, nfleets]