Exception for math.abs on complex

Math

\[\sqrt{re \cdot re + im \cdot im}\]

C

double f(double re, double im) {
        double r8212 = re;
        double r8213 = r8212 * r8212;
        double r8214 = im;
        double r8215 = r8214 * r8214;
        double r8216 = r8213 + r8215;
        double r8217 = sqrt(r8216);
        return r8217;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (re im)
  :name "math.abs on complex"
  (sqrt (+ (* re re) (* im im))))

Backtrace

get-representation: Unknown representation #f		L	C
loop	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	122	4
prepare-points	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	146	0
setup-prog!34	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	67	0
run-improve43	/data/pavpan/nightlies/herbie/interface2/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