Unexpected Compilation Error - potential clash with Function.name?

[mcclaskc]

TypeScript Version: 3.0.1

Search Terms: typescript compilation function name key union es6 compile error

Code
full example on github .

wtf.ts

type MyObject = {
    [index:string]: MyObject | Function | "wtf"
}

let myObj: MyObject;

// compiles
myObj = {
    name: "wtf",
};

// compiles - note the nested key is `notName:`, instead of `name:`
myObj = {
    wrapper: {
        notName: "wtf",
    },
};

// as soon as I change the nested key to `name:`, it fails to compile:
/*
Type '{ name: string; }' is not assignable to type 'Function | MyObject | "wtf"'.
  Type '{ name: string; }' is not assignable to type '"wtf"'
 
*/
myObj = {
    wrapper: {
        name: "wtf",
    },
};


// Other weirdness, if I remove `Function` from the union, it compiles:
type MyObjectNoFunction = {
    [index:string]: MyObjectNoFunction | "wtf"
}

let myObjNoFn: MyObjectNoFunction = {
    wrapper: {
        name: "wtf"
    }
};

// More weirdness, if I don't include es6 in my tsconfig, everything compiles

tsconfig.json

{
  "compilerOptions": {
    "lib": [
      "es6"
    ],
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "noUnusedLocals": true,
    "strict": true
  }
}

Expected behavior:
no compilation errors
Actual behavior:
compilation error:

Type '{ name: string; }' is not assignable to type 'Function | MyObject | "wtf"'.
  Type '{ name: string; }' is not assignable to type '"wtf"'

Corresponding stackoverflow:

Maybe this is because Function has a name property in es6, so TypeScript infers that { name: "something" } is an unfinished Function type declaration
-thedayturns

Playground Link: .
I couldn't get it to happen in playground, but here's a full example on github

Related Issues:

Repro:

interface I { x: number; }
interface Idx { [index: string]: U; }
type U = Idx | I | "lit";
const u: U = { x: "lit" };

No repro if using string instead of "lit".

[sheetalkamat]

The issue here is that string index signature in Idx does not participate in contextual type of property x and thus { x: "lit" } gets widened to { x: string }.