vlib/v/checker/tests/cast_to_interface_err.vv:7:5: notice: condition is always true
    5 | fn foo() !int {
    6 |     // do something
    7 |     if true {
      |        ~~~~
    8 |         return 1
    9 |     }
vlib/v/checker/tests/cast_to_interface_err.vv:20:9: error: `CustomError` doesn't implement method `msg` of interface `IError`
   18 | 
   19 | fn my_error() IError {
   20 |     return IError(CustomError{})
      |            ~~~~~~~~~~~~~~~~~~~~~
   21 | }
vlib/v/checker/tests/cast_to_interface_err.vv:20:9: error: `CustomError` doesn't implement method `code` of interface `IError`
   18 | 
   19 | fn my_error() IError {
   20 |     return IError(CustomError{})
      |            ~~~~~~~~~~~~~~~~~~~~~
   21 | }
vlib/v/checker/tests/cast_to_interface_err.vv:20:9: error: `CustomError` does not implement interface `IError`, cannot cast `CustomError` to interface `IError`
   18 | 
   19 | fn my_error() IError {
   20 |     return IError(CustomError{})
      |            ~~~~~~~~~~~~~~~~~~~~~
   21 | }