plugins/labels: better error message when using imported wallets

see #6703

electrum/plugins/labels/labels.py

@@ -176,8 +176,6 @@ class LabelsPlugin(BasePlugin):
 
     def start_wallet(self, wallet: 'Abstract_Wallet'):
         if not wallet.network: return  # 'offline' mode
-        nonce = self.get_nonce(wallet)
-        self.logger.info(f"wallet {wallet.basename()} nonce is {nonce}")
         mpk = wallet.get_fingerprint()
         if not mpk:
             return
@@ -186,6 +184,8 @@ class LabelsPlugin(BasePlugin):
         iv = hashlib.sha256(password).digest()[:16]
         wallet_id = hashlib.sha256(mpk).hexdigest()
         self.wallets[wallet] = (password, iv, wallet_id)
+        nonce = self.get_nonce(wallet)
+        self.logger.info(f"wallet {wallet.basename()} nonce is {nonce}")
         # If there is an auth token we can try to actually start syncing
         asyncio.run_coroutine_threadsafe(self.pull_safe_thread(wallet, False), wallet.network.asyncio_loop)
 

electrum/plugins/labels/qt.py

@@ -31,12 +31,16 @@ class Plugin(LabelsPlugin):
     def requires_settings(self):
         return True
 
-    def settings_widget(self, window):
+    def settings_widget(self, window: WindowModalDialog):
         return EnterButton(_('Settings'),
                            partial(self.settings_dialog, window))
 
-    def settings_dialog(self, window):
+    def settings_dialog(self, window: WindowModalDialog):
         wallet = window.parent().wallet
+        if not wallet.get_fingerprint():
+            window.show_error(_("{} plugin does not support this type of wallet.")
+                              .format("Label Sync"))
+            return
         d = WindowModalDialog(window, _("Label Settings"))
         hbox = QHBoxLayout()
         hbox.addWidget(QLabel("Label sync options:"))