This is a duplicate of https://www.codewars.com/kata/56d3f1743323a8399200063f (I passed all the tests after translation a solution from Python to JS and do a trivial tweak).

Duplicate: https://www.codewars.com/kata/56a127b14d9687bba200004d

Should work with random invalid grid.
-9 1
expected 0 to equal 1

Although this dosn't make much sense in the first place:

Dimensions can be zero or negative as well. In that case, the answer should be 0.

Tests will go up to grid 50×50.

Results for this size can't be returned as Number, but a Number is expected.