In Number::modulo, it calls Number::ints_to_bigint, which could panic. The reason is that calling .to_integer() isn't enough to guarantee that .to_bigint_owned() will return Some, but Number::ints_to_bigint assumes it will and calls unwrap(). In particular, it might be that it's a float corresponding to an integer that's larger than F64_SAFE_INTEGER. The fix is to not call Number::ints_to_bigint (and indeed to delete that entire function, which is only used in this one place), and instead only call unwrap when Some is returned.
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