gulp-plugin-extras

I came across a few typing issues when working with this tool with TypeScript, so I am fixing them here: Mark optional types as optional Use broader type instead of to be able to work with files of type as well Make optionally async, i.e. return either or Improved (hopefully) definition of AsyncGenerator return type I also would like to be able to work with directly (when performing input checks before creating and returning the plugin itself), so I added it to the in . Thanks for your consideration! Please let me know if you'd like me to make any changes, or split this into two PRs.