DID THE FRICKING isSubType METHOD

Uncommented checkTypes
added some null checking to type checker
added checking for primitives in instance of typeCheck
fixed some bugs in checkBinaryExprNode
deleted useless method checkNotASpecifiedTypeMismatch
DID THE FRICKING isSubType METHOD
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When I run it on a very simple program I’m not getting any errors, so
that’s a good sign.
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