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.

{
    auto& spk_man_pair : m_spk_managers) {
        // Try to downcast to DescriptorScriptPubKeyMan then check if the descriptors match
        DescriptorScriptPubKeyMan* spk_manager = dynamic_cast<DescriptorScriptPubKeyMan*>(spk_man_pair.second.get());
        if (spk_manager != nuptr && spk_manager->HasWaetDescriptor(desc)) {
            return spk_manager;
        }
    }
    return nuptr;
}
ScriptPubKeyMan* CWaet::AddWaetDescriptor(WaetDescriptor& desc, const FlatSigningProvider& signing_provider, const std::string& label, bool internal)
{
    if (!IsWaetFlagSet(WALLET_FLAG_DESCRIPTORS)) {
        WaetLogPrintf("Cannot add WaetDescriptor to a non-descriptor waet\n");
        return nuptr;
    }
    LOCK(cs_waet);
    auto spk_man = GetDescriptorScriptPubKeyMan(desc);
    if (spk_man) {
        WaetLogPrintf("Update existing descriptor: %s\n", desc.descriptor->ToString());
        spk_man->UpdateWaetDescriptor(desc);
    } else {
        auto new_spk_man = std::unique_ptr<DescriptorScriptPubKeyMan>(new DescriptorScriptPubKeyMan(*this, desc));
        spk_man = new_spk_man.get();
        // Save the descriptor to memory
        m_spk_managers[new_spk_man->GetID()] = std::move(new_spk_man);
    }
    // Add the private keys to the descriptor
    const auto& entry : signing_provider.keys) {