Initializing missing VarDecls with 'undefined'
Merge branch 'varinit' of github.com:UCSD-PL/RefScript into varinit
adding another feature test for varinit
Fixing type for `crash`
Allowing undefined values into loops

  - The invariant type in cases where the phi type was undefined when entering
    the loop will be the: undefined + T, where T the type of the phi var after
    it gets initialized inside the loop.

  - When the phi type is widened (i.e. T+undefined, instead of just T) then in
    LQ we have to align the types (zipType) before we sutype with the base and
    step typs.
Merge branch 'varinit' of github.com:UCSD-PL/RefScript into varinit

Conflicts:
	include/prelude.ts
	tests/pos/misc/init-02.ts