Merge pull request #10894 from f321x/fix_qml_use_after_free

### electrum/gui/common_qt/util.py
@@ -1,21 +1,40 @@
 import queue
 import sys
+from contextlib import contextmanager
 from functools import wraps
-from typing import Optional, NamedTuple, Callable
+from typing import Optional, NamedTuple, Callable, Iterator
 import os.path
 
-from PyQt6 import QtGui
-from PyQt6.QtCore import Qt, QThread, pyqtSignal
+from PyQt6 import QtGui, sip
+from PyQt6.QtCore import Qt, QThread, QObject, pyqtSignal
 from PyQt6.QtGui import QColor, QPen, QPaintDevice, QFontDatabase, QImage
 import qrcode
 
 from electrum.i18n import _
-from electrum.logging import Logger
+from electrum.logging import Logger, get_logger
 from electrum.util import EventListener, event_listener
 
+_logger = get_logger(__name__)
+
 _cached_font_ids: dict[str, int] = {}
 
 
+@contextmanager
+def ignore_if_destroyed(qobj: QObject) -> Iterator[None]:
+    """
+    Objects owned by qt (e.g. a child of a dialog) or by QML are destroyed as soon as the user
+    closes the dialog, while threads and tasks may still hold a reference to the python wrapper,
+    and writing a property or emitting a signal on it then raises RuntimeError.
+    Any other RuntimeError is re-raised.
+    """
+    try:
+        yield
+    except RuntimeError:
+        if not sip.isdeleted(qobj):
+            raise
+        _logger.debug(f'{type(qobj).__name__} has been destroyed, ignoring')
+
+
 def get_font_id(filename: str) -> int:
     font_id = _cached_font_ids.get(filename)
     if font_id is not None:

### electrum/gui/qml/qechanneldetails.py
@@ -11,7 +11,7 @@
 from electrum.lnchannel import ChanCloseOption, ChannelState, AbstractChannel, Channel, ChannelBackup
 from electrum.util import format_short_id, event_listener
 
-from electrum.gui.common_qt.util import QtEventListener
+from electrum.gui.common_qt.util import QtEventListener, ignore_if_destroyed
 
 from .auth import AuthMixin, auth_protect
 from .qewallet import QEWallet
@@ -285,17 +285,15 @@ def closeChannel(self, closetype):
     def do_close_channel(self, closetype: str):
         channel_id = self._channel.channel_id
 
+        @ignore_if_destroyed(self)
         def handle_result(success: bool, msg: str = ''):
-            try:
-                if success:
-                    self.channelCloseSuccess.emit()
-                else:
-                    self.channelCloseFailed.emit(msg)
+            if success:
+                self.channelCloseSuccess.emit()
+            else:
+                self.channelCloseFailed.emit(msg)
 
-                self._is_closing = False
-                self.isClosingChanged.emit()
-            except RuntimeError:  # QEChannelDetails might be deleted at this point if the user closed the dialog.
-                pass
+            self._is_closing = False
+            self.isClosingChanged.emit()
 
         def do_close():
             try:

### electrum/gui/qml/qechannelopener.py
@@ -4,10 +4,12 @@
 from typing import Optional
 import electrum_ecc as ecc
 
+from PyQt6 import sip
 from PyQt6.QtCore import pyqtProperty, pyqtSignal, pyqtSlot, QObject, QVariant
 
 from electrum.i18n import _
 from electrum.gui import messages
+from electrum.gui.common_qt.util import ignore_if_destroyed
 from electrum.util import bfh
 from electrum.lnutil import MIN_FUNDING_SAT
 from electrum.lntransport import extract_nodeid, ConnStringFormatError
@@ -230,6 +232,7 @@ def do_open_channel(self, funding_tx: PartialTransaction, conn_str, password):
         funding_sat = funding_tx.output_value_for_address(DummyAddress.CHANNEL)
         lnworker = self._wallet.wallet.lnworker
 
+        @ignore_if_destroyed(self)
         def open_thread():
             error = None
             try:
@@ -253,6 +256,8 @@ def open_thread():
             except (CancelledError, TimeoutError):
                 error = _('Could not connect to channel peer')
             except Exception as e:
+                if isinstance(e, RuntimeError) and sip.isdeleted(self):
+                    return  # qt object already deleted
                 error = str(e)
                 if not error:
                     error = repr(e)
@@ -290,6 +295,7 @@ def calc_max():
                 self._amount.satsInt = amount if amount else 0
             finally:
                 self._updating_max = False
-                self.validate()
+                with ignore_if_destroyed(self):
+                    self.validate()
 
         threading.Thread(target=calc_max, daemon=True).start()

### electrum/gui/qml/qeinvoice.py
@@ -20,7 +20,7 @@
 from electrum.payment_identifier import PaymentIdentifier, PaymentIdentifierState, PaymentIdentifierType
 from electrum.util import event_listener, now, InvoiceError
 
-from electrum.gui.common_qt.util import QtEventListener
+from electrum.gui.common_qt.util import QtEventListener, ignore_if_destroyed
 
 from .qetypes import QEAmount
 from .qewallet import QEWallet
@@ -442,6 +442,7 @@ def updateMaxAmount(self):
 
         self._updating_max = True
 
+        @ignore_if_destroyed(self)
         def calc_max(address):
             try:
                 outputs = [PartialTxOutput(scriptpubkey=address_to_script(address), value='!')]

### electrum/gui/qml/qetxfinalizer.py
@@ -21,7 +21,7 @@
 from electrum.network import NetworkException
 
 from electrum.gui import messages
-from electrum.gui.common_qt.util import QtEventListener
+from electrum.gui.common_qt.util import QtEventListener, ignore_if_destroyed
 
 from .qewallet import QEWallet
 from .qetypes import QEAmount
@@ -1161,6 +1161,7 @@ def make_sweep_tx(self):
     def update_privkeys(self):
         privkeys = keystore.get_private_keys(self._private_keys)
 
+        @ignore_if_destroyed(self)
         def fetch_privkeys_info():
             try:
                 self._txins = self._wallet.wallet.network.run_from_another_thread(sweep_preparations(privkeys, self._wallet.wallet.network))

### electrum/gui/qt/wizard/wallet.py
@@ -25,6 +25,7 @@
 from electrum.wallet_db import WalletDB
 from electrum.wizard import NewWalletWizard, KeystoreWizard, WizardViewState
 
+from electrum.gui.common_qt.util import ignore_if_destroyed
 from electrum.gui.qt.bip39_recovery_dialog import Bip39RecoveryDialog
 from electrum.gui.qt.password_dialog import PasswordLayout, PW_NEW, MSG_ENTER_PASSWORD, PasswordLayoutForHW
 from electrum.gui.qt.seed_dialog import SeedWidget, MSG_PASSPHRASE_WARN_ISSUE4566, KeysWidget
@@ -1175,6 +1176,7 @@ def scan_devices(self):
         self.busy_msg = _('Scanning devices...')
         self.busy = True
 
+        @ignore_if_destroyed(self)
         def scan_task():
             # check available plugins
             supported_plugins = self.plugins.get_hardware_support()

### electrum/hw_wallet/qt.py
@@ -36,7 +36,7 @@
 from electrum.util import UserCancelled, UserFacingException, ChoiceItem
 from electrum.plugin import hook
 
-from electrum.gui.common_qt.util import TaskThread
+from electrum.gui.common_qt.util import TaskThread, ignore_if_destroyed
 from electrum.gui.qt.password_dialog import PasswordLayout, PW_PASSPHRASE
 from electrum.gui.qt.util import (
     read_QIcon, WWLabel, OkButton, WindowModalDialog, Buttons, CancelButton, char_width_in_lineedit, PasswordLineEdit,
@@ -181,10 +181,11 @@ def message_dialog(self, msg, on_cancel=None):
         # window-modal dialog each time is slow and visibly janky on macOS
         # (the modal "sheet" animates closed/open between outputs). See #10718.
         if self.dialog is not None and self._dialog_on_cancel == on_cancel:
-            self._dialog_label.setText(msg)
-            if not self.dialog.isVisible():  # e.g. was hidden by a user "cancel"
-                self.dialog.show()
-            return
+            with ignore_if_destroyed(self.dialog):
+                self._dialog_label.setText(msg)
+                if not self.dialog.isVisible():  # e.g. was hidden by a user "cancel"
+                    self.dialog.show()
+                return  # dialog gets rebuild if a RuntimeError was raised and the return is skipped
         self.clear_dialog()
         title = self.MESSAGE_DIALOG_TITLE
         if title is None:
@@ -207,7 +208,8 @@ def error_dialog(self, msg, blocking):
 
     def clear_dialog(self):
         if self.dialog:
-            self.dialog.accept()
+            with ignore_if_destroyed(self.dialog):
+                self.dialog.accept()
             self.dialog = None
             self._dialog_label = None
             self._dialog_on_cancel = None