error_expr_not_ok.nit:149,14--17: Error: method or variable `fail` unknown in `Sys`.
error_expr_not_ok.nit:149,7--24: Type Error: expected `A`, got `String`.
error_expr_not_ok.nit:150,7--10: Error: method or variable `fail` unknown in `Sys`.
error_expr_not_ok.nit:149,14--17: Error: method or variable `fail` unknown in `Sys`.
error_expr_not_ok.nit:149,7--24: Type Error: expected `A`, got `String`.
error_expr_not_ok.nit:150,7--10: Error: method or variable `fail` unknown in `Sys`.