Broken autoimport of module without index reexport

Demo: https://github.com/zerkalica/ts-references-autoimport-bug/tree/no-autoimport-wo-index

TypeScript Version: 4.0.2
VSCode Version: 1.49.2
OS: Ubuntu 20.04.1 LTS

Example 1

Package 'b' depends on 'a', but 'a' has no index.ts and types in package.json.

Steps to reproduce

1. clone, switch to no-autoimport-wo-index, yarn install
2. Open lib/b/b.ts in vscode, type someA
3. Expected: autoimport suggest import { someA } from '@some/lib-a/a', actual: no autoimport

Example 2

Package 'd' depends only on 'c', 'c' depends on 'a', but 'a' has no index.ts and types in package.json.

Steps to reproduce

1. clone, switch to no-autoimport-wo-index, yarn install
2. Open lib/d/d.ts in vscode, type someA
3. Expected: no someA in autoimport, actual: autoimport suggests broken import { someA } from '../a/a'

克隆链接的 no-autoimport-wo-index 分支，运行 yarn install，并在 lib/b/b.ts 和 lib/d/d.ts 中重现这两种情况。比较实际的和预期的 autoimport 建议，包括 package.json 类型声明；当 Example 1 建议 @some/lib-a/a，而 Example 2 不建议损坏的相对导入时，即可认为该 issue 已完成。