Error message shows core instead of surface language

[countvajhula]

When we provide two arguments instead of one to a flow, (flow f g):

> ((☯ (~>> (sort <)) 2 1 3))
; flow: Syntax error in (flow (thread (#%blanket-template ((#%host-expression sort) (#%host-expression <) __))) (gen (#%host-expression 2)) (gen (#%host-expression 1)) (gen (#%host-expression 3)))
; Usage:
;   (flow flo)
; flow expects a single flow specification, but it received many.
;   in: (flow (thread (#%blanket-template ((#%host-expression sort) (#%host-expression <) __))) (gen (#%host-expression 2)) (gen (#%host-expression 1)) (gen (#%host-expression 3)))

(i.e. all of the 2 1 3 are provided to flow -- it's a typo / misplaced paren)