I have some code like this, except there are about a dozen types instead of just three:

interface Foo {
  kind: "foo";
  name: string;
}
interface Bar {
  kind: "bar";
  name: string;
}
interface Qua {
  kind: "qua";
  length: string;
}

type FBQ = Foo | Bar | Qua;
let x: FBQ = <any>undefined;
console.log(x.name);

The error reported is

a.ts(16,15): error TS2339: Property 'name' does not exist on type 'FBQ'.

This is inactionable on a union type, especially when its consituents are hidden behind an alias. We should show something like

a.ts(16,15): error TS2339: Property 'name' does not exist on type 'FBQ'.
   Property 'name' does not exist on type 'Qua'