qml: emit error when bip21 contains neither an address nor a lightning invoice (fixes #8662)

electrum/gui/qml/qeinvoice.py

@@ -545,13 +545,15 @@ class QEInvoiceParser(QEInvoice):
                     self._validateRecipient_bip21_onchain(self._pi.bip21)
 
     def _validateRecipient_bip21_onchain(self, bip21: Dict[str, Any]) -> None:
-        if 'amount' not in bip21:
-            amount = 0
-        else:
-            amount = bip21['amount']
+        if 'address' not in bip21:
+            self._logger.debug('Neither LN invoice nor address in bip21 uri')
+            self.validationError.emit('unknown', _('Unknown invoice'))
+            return
+
+        amount = bip21.get('amount', 0)
         outputs = [PartialTxOutput.from_address_and_value(bip21['address'], amount)]
         self._logger.debug(outputs)
-        message = bip21['message'] if 'message' in bip21 else ''
+        message = bip21.get('message', '')
         invoice = self.create_onchain_invoice(outputs, message, None, bip21)
         self._logger.debug(repr(invoice))
         self.setValidOnchainInvoice(invoice)