InputFilter: check NickInfoPtr object isn't null before using it
IIUC, if the nick being checked is offline, we can get a nullptr; this also matches how NickInfoPtr object returned by Server::getNickInfo are used in the code.
IIUC, if the nick being checked is offline, we can get a nullptr; this also matches how NickInfoPtr object returned by Server::getNickInfo are used in the code.