The `dumpwallet` RPC command throws an error at the signet node and stops it.
~~This does not happen in mainnet or testnet, where the command worked successfully in my tests..~~
Originally this error was only happening on signet, but it also happened on testnet after it worked successfully for a while.

**Expected behavior**

The RPC `dumpwallet` command is expected to return a success message and create the dump file that contains the private keys.

**Actual behavior**

The command returns an error on client side (`bitcoin-cli`):
`error: timeout on transient error: Could not connect to the server 127.0.0.1:38332 (error code 1 - "EOF reached")
Make sure the bitcoind server is running and that you are connecting to the correct RPC port.`

And it throws an error at the signet node and stops it.

```
POTENTIAL DEADLOCK DETECTED
Previous lock order was:
  'cs_wallet' in wallet/wallet.cpp:2860 (in thread 'httpworker.1')
  (2) '::cs_main' in node/interfaces.cpp:687 (in thread 'httpworker.1')
  'm_node.mempool->cs' in node/interfaces.cpp:687 (in thread 'httpworker.1')
  'cs_wallet' in wallet/wallet.cpp:1204 (in thread 'httpworker.1')
  (1) 'cs_KeyStore' in script/signingprovider.cpp:165 (in thread 'httpworker.1')
Current lock order is:
  'wallet.cs_wallet' in wallet/rpcdump.cpp:743 (in thread 'httpworker.3')
  (1) 'spk_man.cs_KeyStore' in wallet/rpcdump.cpp:743 (in thread 'httpworker.3')
  (1) 'spk_man->cs_KeyStore' in wallet/wallet.cpp:2303 (in thread 'httpworker.3')
  (2) 'cs_main' in node/interfaces.cpp:493 (in thread 'httpworker.3')
Assertion failed: detected inconsistent lock order for 'cs_main' in node/interfaces.cpp:493 (in thread 'httpworker.3'), details in debug log.
Aborted (core dumped)
```

**To reproduce**

Start the node on signet mode:
`bitcoind -signet`

And dump an existing wallet:
`bitcoin-cli -signet -rpcwallet="legacy_wallet_01" dumpwallet "filename"`

**System information**

The bitcoin node was compiled from master (commit: `df2b5dadfb2dc21b05e5a60b71987fb5b96201f5`)
Ubuntu 20.04, 8 CPUs, 12 GiB RAM and SSD.

file.open(filepath);
    if (!file.is_open())
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot open wallet dump file");
    std::map<CKeyID, int64_t> mapKeyBirth;
    const std::map<CKeyID, int64_t>& mapKeyPool = spk_man.GetAllReserveKeys();
    wallet.GetKeyBirthTimes(mapKeyBirth);
    std::set<CScriptID> scripts = spk_man.GetCScripts();
    // 
    std::vector<std::pair<int64_t, CKeyID> > vKeyBirth;
    for (const auto& entry : mapKeyBirth) {
        vKeyBirth.push_back(std::make_pair(entry.second, entry.first));
    }
    mapKeyBirth.clear();
    std::sort(vKeyBirth.begin(), vKeyBirth.end());
    // 
    file << strprintf("# Wallet dump created by Bitcoin %s\n", CLIENT_BUILD);
    file << strprintf("# * Created on %s\n", FormatISO8601DateTime(GetTime()));
    file << strprintf("# * Best block at time of backup was %i (%s),\n", wallet.GetLastBlockHeight(), wallet.GetLastBlockHash().ToString());
    int64_t block_time = 0;
    CHECK_NONFATAL(wallet.chain().findBlock(wallet.GetLastBlockHash(), FoundBlock().time(block_time)));
    file << strprintf("#   mined on %s\n", FormatISO8601DateTime(block_time));
    file << "\n";
    // 
    CKeyID seed_id = spk_man.GetHDChain().seed_id;
    if (!seed_id.IsNull())
    {
        CKey seed;
        if (spk_man.GetKey(seed_id, seed)) {
            CExtKey masterKey;
            masterKey.SetSeed(seed.begin(), seed.size());