qml: veriyMasterKey don't raise Exception on unsupported wallet_type, log error and provide user feedback

electrum/gui/qml/qebitcoin.py

@@ -107,7 +107,6 @@ class QEBitcoin(QObject):
 
     @pyqtSlot(str, str, result=bool)
     def verifyMasterKey(self, key, wallet_type='standard'):
-        # FIXME exceptions raised in here are not well-behaved...
         self.validationMessage = ''
         if not keystore.is_master_key(key):
             self.validationMessage = _('Not a master key')
@@ -126,7 +125,10 @@ class QEBitcoin(QObject):
                     self.validationMessage = '%s: %s' % (_('Wrong key type'), t1)
                     return False
                 return True
-            raise Exception(f'Unsupported wallet type: {wallet_type}')
+            else:
+                self.validationMessage = '%s: %s' % (_('Unsupported wallet type'), wallet_type)
+                self.logger.error(f'Unsupported wallet type: {wallet_type}')
+                return False
         return True
 
     @pyqtSlot(str, result=bool)