[Checkers] Arrays and checkers

[Matt Papi]

>> If there's a type floating around that is invalid 
>> (according to the type validator), is the cause ever the input program 
>> and not a problematic checker?

> It checks that all the valid uses of a type are essentially subtypes of the element declaration type. 

My question (quoted) should have started with "For the @Interned 
checker" -- my fault for not being clear. It doesn't seem like it's 
possible for type validation to fail for the @Interned checker unless 
there's a checker bug. It would be nice for checker developers, and 
certainly less confusing to users, if the framework could catch invalid 
types caused by checker bugs. My original implication was that the type 
validator would do this, but I realize now that it would probably have 
to be a separate mechanism (maybe like the checkRep in NonNull's type 
factory).


Any objections to my proposed fix for the main issue?

- Matt