GeezerVison

Anders Hejlsberg (@ahejlsberg)
Looks like #26698 incorrectly removed a couple of good errors in unions. Specifically, chrome-devtools-frontend has code equivalent to this:

class C {
  constructor(descriptors: (string | symbol | string[])[][]) {
    for (var i = 0; i < descriptors.length; ++i) {
      this[descriptors[i][1]] = // ...... more code here
  }
}

This previously gave the error "string[] cannot be used as an index type", which seems correct to me.