Nigerian airlines have a long history of conning foreign pilots into working for them for free. The standard game is to keep promising that the salary is "coming soon". The longer the pilot stays, the harder it is to walk away from what is "owed". I met an Arik pilot that had been working for free for 13 months, still believing that his back pay was "coming soon". Then as soon as there is a Nigerian pilot available who is type-rated and available, you will lose your work permit anyway, and they probably won't even pay your ticket home as they will accuse you of "breaching your contract". And once you are out of the country you have no chance at all to recover what is owed to you. On top of that, Lagos is just an appalling place to live.