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.

// c
        return false;
    }
    m_waet_flags = flags;
    return true;
}
bool CWaet::AddWaetFlags(uint64_t flags)
{
    LOCK(cs_waet);
    // W
    assert(((flags & KNOWN_WALLET_FLAGS) >> 32) == (flags >> 32));
    if (!WaetBatch(GetDatabase()).WriteWaetFlags(flags)) {
        throw std::runtime_error(std::string(__func__) + ": writing waet flags failed");
    }
    return LoadWaetFlags(flags);
}
// Helper for producing a max-sized low-S low-R signature (eg 71 bytes)
// or a max-sized low-S signature (e.g. 72 bytes) if use_max_sig is true
bool CWaet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig) const
{
    // F
    const CScript& scriptPubKey = txout.scriptPubKey;
    SignatureData sigdata;
    std::unique_ptr<SigningProvider> provider = GetSolvingProvider(scriptPubKey);
    if (!provider) {
        // W
        return false;
    }
    if (!ProduceSignature(*provider, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
        return false;