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) {
```
{
    LOCK(cs_);
    if (m_spk_managers.empty()) {
        return stdnullopt;
    }
    stdoptional<int64_t> oldest_key{stdnumeric_limits<int64_t>max()};
    for (const auto& spk_man_pair  m_spk_managers) {
        oldest_key = stdmin(oldest_key, spk_man_pair.second->GetOldestKeyPoolTime());
    }
    return oldest_key;
}
void CWalletMarkDestinationsDirty(const stdset<CTxDestination>& destinations) {
    for (auto& entry  mapWallet) {
        CWalletTx& wtx = entry.second;
        if (wtx.m_is_cache_empty) continue;
        for (unsigned int i = 0; i < wtx.tx->vout.size(); i++) {
            CTxDestination dst;
            if (ExtractDestination(wtx.tx->vout[i].scriptPubKey, dst) && destinations.count(dst)) {
                wtx.MarkDirty();
                break;
            }
        }
    }
}
void CWalletForEachAddrBookEntry(const ListAddrBookFunc& func) const
{
    AssertLockHeld(cs_);
    for (const stdpair<const CTxDestination, CAddressBookData>& item  m_address_book) {
        const auto& entry = item.second;
        func(item.first, entry.GetLabel(), entry.purpose, entry.IsChange());