Fails to analyze namespaces with top level sexprs which aren't `seqable?`

[matthewdowney]

For example it fails to even run tests in the following namespace:

(defn add [a b] (+ a b))

1

^:rct/test
(comment 
  (add 1 2) ;=> 3
)

I noticed this issue when running on a namespace where I'd accidentally left a literal 1 as a top level form.

In that sense it was helpful, but the code should be updated to reflect that

• there are top-level forms that rewrite-clj says are sexpr-able?
• calling (first (z/sexpr zloc)) on such forms is not necessarily safe