You got lucky.

(additional part of the map removed for clarity)

      x        
1 1 2 2 2      
+ . 1 + .      
1 1 1 1 1  

and

      x        
1 1 2 2 2      
. + 1 . +      
1 1 1 1 1      

Both of there solutions are possible and you made a lucky guess instead of returning '?'

I added those tests now also in final tests. I don't see what makes these tests so special that you would not pass all of those as well.