Properly handle connect errors when initiated from properties dialog.

If connection fails when initiated from the device properties dialog, the
connected page is shown after the update formats worker thread completes.

src/devices/devicemanager.cpp

@@ -586,6 +586,7 @@ void DeviceManager::DeviceConnectFinished(const QString& id, bool success) {
     emit DeviceConnected(idx);
   } else {
     info->device_.reset();
+    emit dataChanged(idx, idx);
   }
 }
 

src/devices/devicemanager.h

@@ -87,6 +87,9 @@ class DeviceManager : public SimpleTreeModel<DeviceInfo> {
   void Disconnect(QModelIndex idx);
   void Forget(QModelIndex idx);
   void UnmountAsync(QModelIndex idx);
+  bool IsConnected(QModelIndex idx) {
+    return GetConnectedDevice(idx) != nullptr;
+  }
 
   void SetDeviceOptions(QModelIndex idx, const QString& friendly_name,
                         const QString& icon_name,

src/devices/deviceproperties.cpp

@@ -264,6 +264,13 @@ void DeviceProperties::OpenDevice() { manager_->Connect(index_); }
 void DeviceProperties::UpdateFormatsFinished(QFuture<bool> future) {
   updating_formats_ = false;
 
+  // Check if the device was disconnected while the thread was running. In that
+  // case, ModelChanged would be called and the not connected page would be
+  // shown.
+  if (!manager_->IsConnected(index_)) {
+    return;
+  }
+
   if (!future.result()) {
     supported_formats_.clear();
   }