With Boost 1.78 (installed on my system), I get a compiler error:

```
./fs.h: In function ‘fs::path fs::operator+(fs::path, fs::path)’:
./fs.h:91:8: error: no match for ‘operator+=’ (operand types are ‘fs::path’ and ‘std::remove_reference<fs::path&>::type’ {aka ‘fs::path’})
   91 |     p1 += std::move(p2);
      |     ~~~^~~~~~~~~~~~~~~~
```

It appears that in Boost 1.78, `operator+=` became a template function, and our `path` class which subclasses `boost::filesystem::path::path` no longer has an `operator+=` which will work with it.

I also opened an issue with boost: https://github.com/boostorg/filesystem/issues/223
{
    for (const std::shared_ptr<CWallet>& pwallet : GetWallets(context)) {
        pwallet->Flush();
    }
}
void StopWallets(WalletContext& context)
{
    for (const std::shared_ptr<CWallet>& pwallet : GetWallets(context)) {
        pwallet->Close();
    }
}
void UnloadWallets(WalletContext& context)
{
    auto wallets = GetWallets(context);
    while (!wallets.empty()) {
        auto wallet = wallets.back();
        wallets.pop_back();
        std::vector<bilingual_str> warnings;
        RemoveWallet(context, wallet, /* l::nullopt, warnings);
        UnloadWallet(std::move(wallet));
    }
}
} // n