Negative Values in JSON Traces

[DavePearce]

(Thanks to @amkCha for pointing this out).

There appears to be some issues with the handling of negative values in json traces. Minimal test:

(module m1)
(defcolumns (X :byte@prove) Y)
(defconstraint c1 () (eq! X Y))

With this trace:

{ "m1": { "X": [1,255,-1], "Y": [1,255,-1] } }

And then this command:

corset check --trace test.json test.lisp

And no failure is reported. Furthermore, with this command:

corset check -eeeeN --trace test.json test.lisp

Then, it crashes.