Exception for fabs fraction 2

Math

\[\frac{\left|a - b\right|}{2} \]

FPCore

(FPCore (a b) :precision binary64 (/ (fabs (- a b)) 2.0))

C

double code(double a, double b) {
	return fabs((a - b)) / 2.0;
}

Fortran

real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = abs((a - b)) / 2.0d0
end function

Java

public static double code(double a, double b) {
	return Math.abs((a - b)) / 2.0;
}

Python

def code(a, b):
	return math.fabs((a - b)) / 2.0

Julia

function code(a, b)
	return Float64(abs(Float64(a - b)) / 2.0)
end

MATLAB

function tmp = code(a, b)
	tmp = abs((a - b)) / 2.0;
end

Wolfram

code[a_, b_] := N[(N[Abs[N[(a - b), $MachinePrecision]], $MachinePrecision] / 2.0), $MachinePrecision]

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022203 
(FPCore (a b)
  :name "fabs fraction 2"
  :precision binary64
  (/ (fabs (- a b)) 2.0))

Backtrace

hash-ref: no value found for key key: '~		L	C
get-parametric-operator	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/syntax.rkt	218	0
f336	.../match/compiler.rkt	548	40
expand-parametric	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/sugar.rkt	62	0
(unnamed)	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt	176	8
generate-rules-for	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt	161	0
generate-missing-rules	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt	187	0
(unnamed)	/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt	29	26
get-swaps	/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt	6	0
connected-components	/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt	17	0
run-improve!	/data/pavpan/nightlies/herbie/enumo-rat/src/mainloop.rkt	296	0
(unnamed)	/data/pavpan/nightlies/herbie/enumo-rat/src/sandbox.rkt	55	6
(unnamed)	/usr/share/racket/pkgs/profile-lib/main.rkt	40	10
profile-thunk	/usr/share/racket/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/usr/share/racket/collects/racket/engine.rkt	42	24