Radioactive exchange between two surfaces

Specification

?
\[\begin{array}{l} \\ {x}^{4} - {y}^{4} \end{array} \]
(FPCore (x y) :precision binary64 (- (pow x 4.0) (pow y 4.0)))
double code(double x, double y) {
	return pow(x, 4.0) - pow(y, 4.0);
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = (x ** 4.0d0) - (y ** 4.0d0)
end function
public static double code(double x, double y) {
	return Math.pow(x, 4.0) - Math.pow(y, 4.0);
}
def code(x, y):
	return math.pow(x, 4.0) - math.pow(y, 4.0)
function code(x, y)
	return Float64((x ^ 4.0) - (y ^ 4.0))
end
function tmp = code(x, y)
	tmp = (x ^ 4.0) - (y ^ 4.0);
end
code[x_, y_] := N[(N[Power[x, 4.0], $MachinePrecision] - N[Power[y, 4.0], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
{x}^{4} - {y}^{4}
\end{array}

Reproduce

?
herbie shell --seed 2024276 
(FPCore (x y)
  :name "Radioactive exchange between two surfaces"
  :precision binary64
  (- (pow x 4.0) (pow y 4.0)))

Please file a bug report with this information.

Backtrace

error: contract violation expected: string? given: 'pow.f64LC
f463.../match/compiler.rkt55940
loop.../private/map.rkt4019
loop.../private/map.rkt4019
loop.../private/map.rkt4019
compile-expr/home/nightlies/herbie/bhargav-log-space/src/core/explain.rkt830
explain/home/nightlies/herbie/bhargav-log-space/src/core/explain.rkt7120
explain!/home/nightlies/herbie/bhargav-log-space/src/core/mainloop.rkt3230
run-improve!/home/nightlies/herbie/bhargav-log-space/src/core/mainloop.rkt450
get-alternatives/report/home/nightlies/herbie/bhargav-log-space/src/api/sandbox.rkt1860
(unnamed)/home/nightlies/herbie/bhargav-log-space/src/api/sandbox.rkt2826
(unnamed)/usr/share/racket/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/share/racket/pkgs/profile-lib/main.rkt90
(unnamed)/usr/share/racket/collects/racket/engine.rkt4224