"null" as a value, struct bugfixes

[ballercat]

• Makes sure structs within structs are handled correctly (like a linked list type for example) during access. So that accessed fields always have the correct type.
• Add's support for null

[coveralls]

Pull Request Test Coverage Report for Build 254

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 99.666%

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Totals
Change from base Build 247:	0.002%
Covered Lines:	1939
Relevant Lines:	1939

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💛 - Coveralls

[JobLeonard]

Add's support for null

Why not take this opportunity to fix the billion dollar mistake? :P

[JobLeonard]

Reference: https://www.infoq.com/presentations/Null-References-The-Billion-Dollar-Mistake-Tony-Hoare

(and of course I know we can't avoid pointers in this context. Still a good watch!)