* Make decode module return value `ImageData`
* Fix global definition of ImageData
* Use concrete Encoder types for encode functions
* Use ArrayBufferView in FileLike instead of using a similar type
* Throw error when the `encode` functions
return null
* Use generic types for WorkerPool
* Fix `encode` function typing
in `index.ts`
* Remove ts-ignore for web-streams-polyfill
and handle nulls for TransformStream
* Fix rollup entry point (now we need to have
`index.ts` instead of `index.js`)
