Steps to reproduce:

* Build with `integer` sanitizer
* Start: `UBSAN_OPTIONS="suppressions=$(pwd)/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1" ./src/qt/bitcoin-qt -chain=main`
* Enter `getdescriptorinfo "sh(multi(1,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,[00000000]xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/58)0)"` into the console
{
    AssertLockHeld(cs_desc_man);
    std::unique_ptr<FlatSigningProvider> out_keys = std::make_unique<FlatSigningProvider>();
    
    auto it = m_map_signing_providers.find(index);
    if (it != m_map_signing_providers.end()) {
        *out_keys = Merge(*out_keys, it->second);
    } else {
        
        std::vector<CScript> scripts_temp;
        if (!m_wallet_descriptor.descriptor->ExpandFromCache(index, m_wallet_descriptor.cache, scripts_temp, *out_keys)) return nullptr;
        
        m_map_signing_providers[index] = *out_keys;
    }
    if (HavePrivateKeys() && include_private) {
        FlatSigningProvider master_provider;
        master_provider.keys = GetKeys();
        m_wallet_descriptor.descriptor->ExpandPrivate(index, master_provider, *out_keys);
    }
    return out_keys;
}
std::unique_ptr<SigningProvider> DescriptorScriptPubKeyMan::GetSolvingProvider(const CScript& script) const
{
    return GetSigningProvider(script, false);
}
bool DescriptorScriptPubKeyMan::CanProvide(const CScript& script, SignatureData& sigdata)
{
    return IsMine(script);
}
bool DescriptorScriptPubKeyMan::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, bilingual_str>& input_errors) const