Add nullptr guard-check in comparision of shared ptr node and edge

[badumbatish]

Fixes Clang's critical bug on the library where we're doing custom shared_ptr comparison with potentially null ptrs.

This will fix #433 but i think what we should also be doing is enforce nullptr safety on these custom operators on shared ptrs

This allows Clang on MacOS to pass all tests.

• A description of the changes proposed in the pull request. I added

...
  if (p1 == nullptr && p2 == nullptr) return true;
  if (p1 == nullptr || p2 == nullptr) return false;
...

to == operator in PointerHash()

@ZigRazor would love a review

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.87%. Comparing base (1b31e63) to head (80e69fd). Report is 25 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #436      +/-   ##
==========================================
+ Coverage   97.58%   97.87%   +0.28%     
==========================================
  Files          87       87              
  Lines        9492    10063     +571     
  Branches        0      670     +670     
==========================================
+ Hits         9263     9849     +586     
+ Misses        229      214      -15     

Flag	Coverage Δ
unittests	97.87% <100.00%> (+0.28%)	:arrow_up:

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[ZigRazor]

We are waiting the re-liensing #427, after that we can merge it!

[badumbatish]

how should i pass the rest of the tests on ci/cd ? @ZigRazor

[ZigRazor]

how should i pass the rest of the tests on ci/cd ? @ZigRazor

The only one you can pass is the clang format, just formatting with clang. @badumbatish The ore CI/CD should be fix, now aren't working