vlib/v/checker/tests/array_of_sumtype_append_err.vv:9:9: error: cannot append `[]string` to `[]Bar`
    7 | fn main() {
    8 |     mut bar := []Bar{}
    9 |     bar << ['hey']
      |            ~~~~~~~
   10 |     bar << 'hey'
   11 | }
vlib/v/checker/tests/array_of_sumtype_append_err.vv:10:9: error: cannot append `string` to `[]Bar`
    8 |     mut bar := []Bar{}
    9 |     bar << ['hey']
   10 |     bar << 'hey'
      |            ~~~~~
   11 | }