Possible "index out of range" in `equalMarks`

Hello!

I'm interested in carefree [iteration](https://github.com/cockroachdb/errors/blob/217058372e2042c4d08384adbd883316372f1070/markers/markers.go#L200) over lists whose lengths can vary:
```go
// equalMarks compares two error markers.
func equalMarks(m1, m2 errorMark) bool {
if m1.msg != m2.msg {
return false
}
for i, t := range m1.types {
if !t.Equals(m2.types[i]) {
return false
}
}
return true
}
```

And I made an example that breaks this code:
```go
package main

import (
"fmt"
"github.com/cockroachdb/errors"
)

type SimpleWrapper struct {
err error
}

func (w SimpleWrapper) Error() string {
return "boom!"
}

func (w SimpleWrapper) Unwrap() error {
return w.err
}

func main() {
stack := errors.WithStack

ref := stack(stack(SimpleWrapper{}))
err := stack(stack(SimpleWrapper{err: stack(errors.New("boom!"))}))

if errors.IsAny(err, ref) {
fmt.Println("gotcha!")
}

/* panic: runtime error: index out of range [3] with length 3

goroutine 1 [running]:
github.com/cockroachdb/errors/markers.equalMarks(...)
github.com/cockroachdb/errors@v1.9.0/markers/markers.go:205
github.com/cockroachdb/errors/markers.IsAny({0x102802528, 0x1400000e438}, {0x14000167f48, 0x1, 0x14000167f28?})
github.com/cockroachdb/errors@v1.9.0/markers/markers.go:186 +0x364
github.com/cockroachdb/errors.IsAny(...)
github.com/cockroachdb/errors@v1.9.0/markers_api.go:64
main.main()
examples/04-non-standard-modules/cockroach-is-any-bug/main.go:26 +0x318
*/
}
```

Where am I wrong?