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) {
```
}
    }
    const PrecomputedTransactionData txdata = PrecomputePSBTData(psbtx);
    // Fill in information from ScriptPubKeyMans
    for (ScriptPubKeyMan* spk_man  GetAllScriptPubKeyMans()) {
        int n_signed_this_spkm = 0;
        TransactionError res = spk_man->FillPSBT(psbtx, txdata, sighash_type, sign, bip32derivs, &n_signed_this_spkm, finalize);
        if (res != TransactionErrorOK) {
            return res;
        }
        if (n_signed) {
            (*n_signed) += n_signed_this_spkm;
        }
    }
    // Only drop non_witness_utxos if sighash_type != SIGHASH_ANYONECANPAY
    if ((sighash_type & 0x80) != SIGHASH_ANYONECANPAY) {
        // Figure out if any non_witness_utxos should be dropped
        stdvector<unsigned int> to_drop;
        for (unsigned int i = 0; i < psbtx.inputs.size(); ++i) {
            const auto& input = psbtx.inputs.at(i);
            int wit_ver;
            stdvector<unsigned char> wit_prog;
            if (input.witness_utxo.IsNull() || !input.witness_utxo.scriptPubKey.IsWitnessProgram(wit_ver, wit_prog)) {
                // There's 
                to_drop.clear();
                break;
            }
            if (wit_ver == 0) {
                // Segwit 
                to_drop.clear();