vlib/v/checker/tests/is_type_invalid.vv:14:2: error: cannot use type `byte` as type `IoS`
   12 |
   13 | fn main() {
   14 |     if IoS(1) is byte {
      |     ~~~~~~~~~~~~~~~~~
   15 |         println('not cool')
   16 |     }
vlib/v/checker/tests/is_type_invalid.vv:18:2: error: `Cat` doesn't implement method `speak`
   16 |     }
   17 |     a := Animal(Dog{})
   18 |     if a is Cat {
      |     ~~~~~~~~~~~
   19 |         println('not cool either')
   20 |     }
