Attempt to restore a non-readable wallet.dat silently crashes the GUI client #661

2022-09-04T19:17:59Z GUI: Qt has caught an exception thrown from an event handler. Throwing
exceptions from an event handler is not supported in Qt.
You must not let any exception whatsoever propagate through Qt code.
If that is not possible, in Qt 5 you must at least reimplement
QCoreApplication::notify() and catch all exceptions there.

terminate called after throwing an instance of 'std::filesystem::__cxx11::filesystem_error'
  what():  filesystem error: cannot copy file: Permission denied [/tmp/usehd0.dat] [/home/dev/.bitcoin/regtest/wallets/nonHD/wallet.dat]
Aborted

Two issues here:

1. Unhandled exceptions should be displayed in the GUI before quitting.
2. Failure to restore a wallet should not crash.

When this feature was merged, this use case was working. It seems this bug was introduced later (as suggested in https://github.com/bitcoin/bitcoin/issues/26004). Perhaps automated GUI tests can avoid this kind of error.