Directly setting an object which contains an optional item defined with an interface doesn't bypass `Object is possibly 'null' or 'undefined'.`

TypeScript Version: 3.9.0-dev.20200305

Search Terms:

• object is possibly 'null' or 'undefined'

Code
https://github.com/mckaysalisbury/typescript-direct-set

// See the above repo for a little more self containment.
// Most notably `"strictNullChecks": true`
interface I {
  optional?: (I | null);
  required: number;
}

let workaround: I;
workaround = {
  optional: { required: 2 },
  required: 1
};

workaround.optional.required;  // This is where the error occurs

Expected behavior:
This code should properly compile without errors, even with "strictNullChecks": true
Actual behavior:
With "strictNullChecks": true, there is a possibly undefined error.

Playground Link:
Typescript Playground

Related Issues:

• https://github.com/microsoft/TypeScript/issues/35523
  Not that related
• https://github.com/microsoft/TypeScript/issues/36193
• https://github.com/microsoft/TypeScript/issues/35964

リンク先の TypeScript Playground で strictNullChecks を有効にして例を再現し、その後、関連する issue を読んでこの動作についての既存の議論を確認してください。直接オブジェクト代入の後にコンパイラーがオプショナルプロパティを絞り込むべきかどうかを判断してください。変更が受け入れられる場合に例をカバーするリグレッションテストが追加され、合意された動作が決まれば完了です。