Diagnostics includes path before message

[rktjmp]

Sometimes Fennel gives us error with an embedded path in it. We correctly strip the first location but the second is shown in the diagnostic - obscuring the message.

Eg: Fennel gives us

/path/my/file.fnl:4:4 Compile error: /path/my/file.fnl:5:18 Compile error: can't nest multi-value destructuring

      (where (< t (/ 1 6))) (-> (- q p) (* 6 t) (+ p))

Which we convert into

{:file "/path/my/file.fnl"
 :loc [4 4]
 :message "Compile error: /path/my/file.fnl:5:18 Compile error: can't nest multi-value destructuring"}

Offending code

    (case t
      (where (< t (/ 1 6))) (-> (- q p) (* 6 t) (+ p))
      (where (< t (/ 1 2))) q
      (where (< t (/ 2 3))) (-> (- q p) (* (- (/ 2 3) t) 6))
      _ p)