qt.util.MyTreeView: handle find_row_by_key returning None

fixes https://github.com/spesmilo/electrum/issues/7780
fixes https://github.com/spesmilo/electrum/issues/7815

Re FIXME in main_window.py, in particular, adb might call `add_transaction` on the same tx multiple times.
In `wallet.on_event_adb_added_tx`, maybe we should propagate `notify_GUI` to `wallet._update_request_statuses_touched_by_tx`.

The issue being fixed here (above TARS reports) can be triggered in multiple ways, e.g.:
- have an already paid receive request, and receive a payment to the same address again
- have an already paid receive request, and *spend from* that address (in which case the history of the address will change, and address_synchronizer will call add_transaction again on the old tx that satisfied the old receive request)

electrum/gui/qt/address_list.py

@@ -215,6 +215,7 @@ class AddressList(MyTreeView):
         self.proxy.setDynamicSortFilter(True)
 
     def refresh_row(self, key, row):
+        assert row is not None
         address = key
         label = self.wallet.get_label(address)
         num = self.wallet.adb.get_address_history_len(address)

electrum/gui/qt/invoice_list.py

@@ -75,6 +75,7 @@ class InvoiceList(MyTreeView):
         self.setSelectionMode(QAbstractItemView.ExtendedSelection)
 
     def refresh_row(self, key, row):
+        assert row is not None
         invoice = self.parent.wallet.invoices.get(key)
         if invoice is None:
             return

electrum/gui/qt/main_window.py

@@ -1817,6 +1817,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         if req is None:
             return
         if status == PR_PAID:
+            # FIXME notification should only be shown if request was not PAID before
             msg = _('Payment received:')
             amount = req.get_amount_sat()
             if amount:

electrum/gui/qt/request_list.py

@@ -105,6 +105,7 @@ class RequestList(MyTreeView):
         self.selectionModel().clearCurrentIndex()
 
     def refresh_row(self, key, row):
+        assert row is not None
         model = self.std_model
         request = self.wallet.get_request(key)
         if request is None:

electrum/gui/qt/util.py

@@ -794,7 +794,7 @@ class MyTreeView(QTreeView):
         self._pending_update = defer
         return defer
 
-    def find_row_by_key(self, key):
+    def find_row_by_key(self, key) -> Optional[int]:
         for row in range(0, self.std_model.rowCount()):
             item = self.std_model.item(row, 0)
             if item.data(self.key_role) == key:
@@ -806,15 +806,21 @@ class MyTreeView(QTreeView):
             key = item.data(self.key_role)
             self.refresh_row(key, row)
 
+    def refresh_row(self, key: str, row: int) -> None:
+        pass
+
     def refresh_item(self, key):
         row = self.find_row_by_key(key)
-        self.refresh_row(key, row)
+        if row is not None:
+            self.refresh_row(key, row)
 
     def delete_item(self, key):
         row = self.find_row_by_key(key)
-        self.std_model.takeRow(row)
+        if row is not None:
+            self.std_model.takeRow(row)
         self.hide_if_empty()
 
+
 class MySortModel(QSortFilterProxyModel):
     def __init__(self, parent, *, sort_role):
         super().__init__(parent)

electrum/gui/qt/utxo_list.py

@@ -114,6 +114,7 @@ class UTXOList(MyTreeView):
             self.parent.set_coincontrol_msg(None)
 
     def refresh_row(self, key, row):
+        assert row is not None
         utxo = self._utxo_dict[key]
         utxo_item = [self.std_model.item(row, col) for col in self.Columns]
         address = utxo.address