Type checking error upgrading from TypeScript 3.5 to 3.6

test.ts

import EmberObject, { set } from "@ember/object"

class Foo extends EmberObject {
  public version!: number
}

class Bar extends EmberObject {
  public version!: number
  public name!: string // Note: removing this line makes the error below go away
}

function test(a: Foo | Bar) {
  // Global set type checks correctly, no problems here
  set(a, "version", 1)

  // But using .set() gives `error TS2349: This expression is not callable.`
  a.set("version", 1)
}

This is still happening with TypeScript 3.7.2.