prefixer middleware does not copy element type

[quantizor]

When running prefixer over an element node like a keyframes object, the prefixed version is created but element.type is not set to "@keyframes", it gets set to an empty string

[thysultan]

Example code?

[quantizor]

import { compile, Middleware, middleware, prefixer, serialize, stringify } from 'stylis';

const stylis = (css: string, extraPlugins: Middleware[] = []) =>
  serialize(compile(css), middleware([...extraPlugins, stringify]));

stylis(
  `@keyframes a {
    0% { left: 0px; }
    100% { left: 100px; }
  }
`,
  [prefixer]
)

The new keyframe rule generated by the prefixer plugin has element.type set to empty string instead of "@keyframes"

[Andarist]

Just a note about the current implementation - the third argument passed here is for the type and it is set to '':
https://github.com/thysultan/stylis.js/blob/e6843c373ebcbbfade25ebcc23f540ed8508da0a/src/Middleware.js#L48

Looking into the codebase - all calls to copy pass an empty string there.

[thysultan]

Pending accidental fix with the next patch i'm working on.