https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=56270
privkey.Sign(uint256S(""), sig);
            sig.push_back(1); 
            dummy_sigs.insert({pubkey, {sig, i & 1}});
            std::vector<unsigned char> hash;
            hash.resize(32);
            CSHA256().Write(keydata, 32).Finalize(hash.data());
            sha256.push_back(hash);
            if (i & 1) sha256_preimages[hash] = std::vector<unsigned char>(keydata, keydata + 32);
            CHash256().Write(keydata).Finalize(hash);
            hash256.push_back(hash);
            if (i & 1) hash256_preimages[hash] = std::vector<unsigned char>(keydata, keydata + 32);
            hash.resize(20);
            CRIPEMD160().Write(keydata, 32).Finalize(hash.data());
            assert(hash.size() == 20);
            ripemd160.push_back(hash);
            if (i & 1) ripemd160_preimages[hash] = std::vector<unsigned char>(keydata, keydata + 32);
            CHash160().Write(keydata).Finalize(hash);
            hash160.push_back(hash);
            if (i & 1) hash160_preimages[hash] = std::vector<unsigned char>(keydata, keydata + 32);
        }
    }
} TEST_DATA;
/**
 * Context to parse a Miniscript node to and from Script or text representation.
 * Uses an integer (an index in the dummy keys array from the test data) as keys in order
 * to focus on fuzzing the Miniscript nodes' test representation, not the key representation.
 */
struct ParserContext {
    typedef CPubKey Key;
    bool KeyCompare(const Key& a, const Key& b) const {