Updated test to cover null values for defined variables.
Added test case for when an param built through an aliased typehint is missing a definition for one of it's parameters.
Added bugfix to get correct exception message for the above.
Added function comment.
Merge branch 'masterExceptionRefactor' into danackExceptionRefactor

* masterExceptionRefactor:
  Added function comment.
  Added test case for when an param built through an aliased typehint is missing a definition for one of it's parameters. Added bugfix to get correct exception message for the above.
  Updated test to cover null values for defined variables.