By Canadian tradition the Liberals would be granted the opportunity to form government first.  If they prove unable to form a government the Lieutenant Governor has the option to either ask the NDP to form a government or to call an election.

Also of note the Speaker of the House does not vote on most matters unless there is a tie, so the Liberals will almost certainly not select any  of their own members opting instead to get an NDP or Green MP to be speaker.  That will result in 43 MPs for the liberals and 43 for the NDP and Greens combined with the Speaker (NDP or Green) being the tie-breaking vote.

.. of course most votes won't have every single MP available to vote.  So at the end of the day the Liberals will likely be able to govern as if they have a majority.

... of course a single by-election could change everything.