Have this warning while building current master (0bd4929cd00e91bf4137f43b097cd62f72f503e4) on one test machine.
```
wallet/rpcwallet.cpp: In function 'rescanblockchain()::<lambda(const RPCHelpMan&, const JSONRPCRequest&)>':
wallet/rpcwallet.cpp:3596:19: warning: '*((void*)& stop_height +4)' may be used uninitialized in this function [-Wmaybe-uninitialized]
 3596 |     Optional<int> stop_height;
      |                   ^~~~~~~~~~~
```
```
$ gcc --version
gcc (Gentoo 9.2.0-r2 p3) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ uname -a
Linux red-box 4.19.72-gentoo #2 SMP Sun Sep 22 03:00:01 EEST 2019 x86_64 Intel(R) Pentium(R) CPU N3710 @ 1.60GHz GenuineIntel GNU/Linux
```
{
    if (URL_DECODE && request.URI.substr(0, WALLET_ENDPOINT_BASE.size()) == WALLET_ENDPOINT_BASE) {
        
        wallet_name = URL_DECODE(request.URI.substr(WALLET_ENDPOINT_BASE.size()));
        return true;
    }
    return false;
}
std::shared_ptr<CWallet> GetWalletForJSONRPCRequest(const JSONRPCRequest& request)
{
    CHECK_NONFATAL(!request.fHelp);
    std::string wallet_name;
    if (GetWalletNameFromJSONRPCRequest(request, wallet_name)) {
        std::shared_ptr<CWallet> pwallet = GetWallet(wallet_name);
        if (!pwallet) throw JSONRPCError(RPC_WALLET_NOT_FOUND, "Requested wallet does not exist or is not loaded");
        return pwallet;
    }
    std::vector<std::shared_ptr<CWallet>> wallets = GetWallets();
    if (wallets.size() == 1) {
        return wallets[0];
    }
    if (wallets.empty()) {
        throw JSONRPCError(
            RPC_WALLET_NOT_FOUND, "No wallet is loaded. Load a wallet using loadwallet or create a new one with createwallet. (Note: A default wallet is no longer automatically created)");
    }
    throw JSONRPCError(RPC_WALLET_NOT_SPECIFIED,
        "Wallet file not specified (must request wallet RPC through /wallet/<filename> uri-path).");
}
void EnsureWalletIsUnlocked(const CWallet* pwallet)