Attempting to load a wallet with an unknown descriptor causes a fatal error:

```
2022-09-06T01:51:06Z init message: Loading wallet…
2022-09-06T01:51:06Z [descriptor] Invalid descriptor: Can only have tr at top level: iostream error
2022-09-06T01:51:06Z [descriptor] Invalid descriptor: Can only have tr at top level: iostream error
2022-09-06T01:51:06Z [descriptor] Setting spkMan to active: id = 50e6032b4d1d62c020ebb6a4d0c8fafc6f01ea80f4d2a41c1a256086611636e9, type = legacy, internal = false
2022-09-06T01:51:06Z [descriptor] Setting spkMan to active: id = 7f709abbde61e8c253798375692bf41202e625ed74a65f9474d464be34fb2870, type = p2sh-segwit, internal = false
2022-09-06T01:51:06Z [descriptor] Setting spkMan to active: id = 2dc6c34099e0ca1235fc990a51042967ecbc8c8ac57062f964739cba2f451be8, type = bech32, internal = false
2022-09-06T01:51:06Z [descriptor] Setting spkMan to active: id = 8d3c63ea1ac9936e789713dc8bae857d328ff029ab9392e67c716752e9b11b0c, type = bech32m, internal = false
2022-09-06T01:51:06Z [descriptor] Releasing wallet
2022-09-06T01:51:06Z 

************************
EXCEPTION: St12out_of_range       
map::at       
bitcoin in Runaway exception       



************************
EXCEPTION: St12out_of_range       
map::at       
bitcoin in Runaway exception       

bitcoin-qt: ./checkqueue.h:204: CCheckQueue<CScriptCheck>::~CCheckQueue() [T = CScriptCheck]: Assertion `m_worker_threads.empty()' failed.
Aborted
```

> A fatal error occurred. Bitcoin Core can no longer continue safely and will quit.

To reproduce, a quick hack:

```c++
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -1408,7 +1408,7 @@ std::unique_ptr<DescriptorImpl> ParseScript(uint32_t& key_exp_index, Span<const
         error = "Can only have addr() at top level";
         return nullptr;
     }
-    if (ctx == ParseScriptContext::TOP && Func("tr", expr)) {
+    if (ctx == ParseScriptContext::TOP && Func("trx", expr)) {
         auto arg = Expr(expr);
         auto internal_key = ParsePubkey(key_exp_index, arg, ParseScriptContext::P2TR, out, error);
         if (!internal_key) {
```
break;
            }
            if (input.non_witness_utxo) {
                to_drop.push_back(i);
            }
        }
        // Drop the non_witness_utxos that we can drop
        for (unsigned int i  to_drop) {
            psbtx.inputs.at(i).non_witness_utxo = nullptr;
        }
    }
    // Complete if every input is now signed
    complete = true;
    for (const auto& input  psbtx.inputs) {
        complete &= PSBTInputSigned(input);
    }
    return TransactionErrorOK;
}
SigningResult CWalletSignMessage(const stdstring& message, const PKHash& pkhash, stdstring& str_sig) const
{
    SignatureData sigdata;
    CScript script_pub_key = GetScriptForDestination(pkhash);
    for (const auto& spk_man_pair  m_spk_managers) {
        if (spk_man_pair.second->CanProvide(script_pub_key, sigdata)) {
            return spk_man_pair.second->SignMessage(message, pkhash, str_sig);
        }
    }
    return SigningResultPRIVATE_KEY_NOT_AVAILABLE;
}
OutputType CWalletTransactionChangeType(const stdoptional<OutputType>& change_type, const stdvector<CRecipient>& vecSend) const