alt/base_as_notnull2_alt1.nit:30,12: Warning: expression is not null, since it is a `Object`.
alt/base_as_notnull2_alt1.nit:50,12: Warning: expression is not null, since it is a `F: Object`.
alt/base_as_notnull2_alt1.nit:58,7--10: Type Error: expected `Object`, got `null`.