Exception for exp neg sub

Math

\[e^{-\left(1 - x \cdot x\right)}\]

C

double f(double x) {
        double r2436104 = 1.0;
        double r2436105 = x;
        double r2436106 = r2436105 * r2436105;
        double r2436107 = r2436104 - r2436106;
        double r2436108 = -r2436107;
        double r2436109 = exp(r2436108);
        return r2436109;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019173 +o rules:numerics
(FPCore (x)
  :name "exp neg sub"
  (exp (- (- 1.0 (* x x)))))

Backtrace

hash-ref: no value found for key key: #<enode 84(84)>		L	C
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	197	2
extractor-extract	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	196	0
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	35	2
(unnamed)	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	26	0
simplify!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	217	0
run-iter!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	320	0
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	354	4
run-improve43	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	339	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28