qml: QETxFinalizer: handle txid being None

fixes https://github.com/spesmilo/electrum/issues/10042

electrum/gui/qml/qetxdetails.py

@@ -509,5 +509,7 @@ class QETxDetails(QObject, QtEventListener):
     @pyqtSlot(result='QVariantList')
     def getSerializedTx(self):
         txqr = self._tx.to_qr_data()
-        label = self._wallet.wallet.get_label_for_txid(self._tx.txid())
+        label = ""
+        if txid := self._tx.txid():
+            label = self._wallet.wallet.get_label_for_txid(txid)
         return [str(self._tx), txqr[0], txqr[1], label]

electrum/gui/qml/qetxfinalizer.py

@@ -495,7 +495,9 @@ class QETxFinalizer(TxFeeSlider):
     @pyqtSlot(result='QVariantList')
     def getSerializedTx(self):
         txqr = self._tx.to_qr_data()
-        label = self._wallet.wallet.get_label_for_txid(self._tx.txid())
+        label = ""
+        if txid := self._tx.txid():
+            label = self._wallet.wallet.get_label_for_txid(txid)
         return [str(self._tx), txqr[0], txqr[1], label]
 
 

electrum/gui/qt/history_list.py

@@ -256,7 +256,8 @@ class HistoryModel(CustomModel, Logger):
 
     def update_label(self, index):
         tx_item = index.internalPointer().get_data()
-        tx_item['label'] = self.window.wallet.get_label_for_txid(get_item_key(tx_item))
+        tx_item['label'] = self.window.wallet.get_label_for_txid(
+            get_item_key(tx_item))  # FIXME get_item_key might return an RHASH, but we call get_label_for_txid?!
         topLeft = bottomRight = self.createIndex(index.row(), HistoryColumns.DESCRIPTION)
         self.dataChanged.emit(topLeft, bottomRight, [Qt.ItemDataRole.DisplayRole])
         self.window.utxo_list.update()

electrum/wallet.py

@@ -1683,7 +1683,8 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         self._default_labels['group:' + group_id] = label
 
     def get_label_for_txid(self, tx_hash: str) -> str:
-        return self._labels.get(tx_hash) or self._get_default_label_for_txid(tx_hash)
+        assert tx_hash, f"expected a txid, got {tx_hash!r}"
+        return self._labels.get(tx_hash) or self._get_default_label_for_txid(tx_hash) or ""
 
     def _get_default_label_for_txid(self, tx_hash: str) -> str:
         if label := self._default_labels.get(tx_hash):