## Issue being fixed or feature implemented
Current implementation relies either on asserts or sometimes checks then
returning a special value; In the case of asserts (or no assert where we
use the value without checks) it'd be better to make it explicit to
function caller that the ptr must be not_null; otherwise gsl::not_null
will call terminate.
See
https://github.com/microsoft/GSL/blob/main/docs/headers.md#user-content-H-pointers-not_null
and
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rf-nullptr
I'm interested in a conceptual review; specifically on if this is
beneficial over just converting these ptrs to be a reference?
## What was done?
*Partial* implementation on using gsl::not_null in dash code
## How Has This Been Tested?
Building
## Breaking Changes
None
## Checklist:
_Go over all the following points, and put an `x` in all the boxes that
apply._
- [x] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have added or updated relevant unit/integration/functional/e2e
tests
- [ ] I have made corresponding changes to the documentation
- [x] I have assigned this pull request to a milestone _(for repository
code-owners and collaborators only)_
---------
Signed-off-by: pasta <pasta@dashboost.org>
Co-authored-by: UdjinM6 <UdjinM6@users.noreply.github.com>
