fix: Now cannot send party invite to a friend which has "Offline" status

Fix #4018

src/widget/form/groupchatform.cpp

@@ -298,7 +298,9 @@ void GroupChatForm::dropEvent(QDropEvent *ev)
 
     int friendId = frnd->getFriendId();
     int groupId = group->getGroupId();
-    Core::getInstance()->groupInviteFriend(friendId, groupId);
+    if (frnd->getStatus() != Status::Offline) {
+        Core::getInstance()->groupInviteFriend(friendId, groupId);
+    }
 }
 
 void GroupChatForm::onMicMuteToggle()

src/widget/friendwidget.cpp

@@ -113,6 +113,7 @@ void FriendWidget::onContextMenuCalled(QContextMenuEvent *event)
 
     menu.addSeparator();
     QMenu* inviteMenu = menu.addMenu(tr("Invite to group","Menu to invite a friend to a groupchat"));
+    inviteMenu->setEnabled(getFriend()->getStatus() != Status::Offline);
     QAction* newGroupAction = inviteMenu->addAction(tr("To new group"));
     inviteMenu->addSeparator();
     QMap<QAction*, Group*> groupActions;

src/widget/groupwidget.cpp

@@ -258,7 +258,9 @@ void GroupWidget::dropEvent(QDropEvent *ev)
         return;
 
     int friendId = frnd->getFriendId();
-    Core::getInstance()->groupInviteFriend(friendId, groupId);
+    if (frnd->getStatus() != Status::Offline) {
+        Core::getInstance()->groupInviteFriend(friendId, groupId);
+    }
 
     if (!active)
         setBackgroundRole(QPalette::Window);