Type incorrect on decorator metadata when unioning null

[gregarcara]

Describe the bug

When unioning null the type on the decorator metadata is Object when for example it is string | null the type should be string. This is causing issues when using type-graphql and typeorm. This is similar to #2703

Input code

import 'reflect-metadata';

const COL_KEY = Symbol('col');

const column = () => {
    return (object: any, key: string) => {
        Reflect.defineMetadata(COL_KEY, 'value', object, key);
    };
};

class User {
    @column() currency!: string | null;
}

console.log(Reflect.getMetadata('design:type', User.prototype, 'currency'));

Config

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "decorators": true
    },
    "transform": {
      "legacyDecorator": true,
      "decoratorMetadata": true
    },
    "target": "es2019",
    "keepClassNames": true
  },
  "module": {
     "type": "commonjs"
   }
}

Playground link

https://play.swc.rs/?version=1.2.133&code=H4sIAAAAAAAAA02PwWrDMAyG73kK7WQH0jxAQstg9NSNwUYPOw3XUUM2xw6yPDBd3312k5TpZsn6v0%2FDODliEIRng5o3I7LqFCvRFoV21jM8vT5%2FHvYfsIX3OJ6ckUI7I8r7PL3CaNNYlrDdwaWAVIQcyIJ0p6%2BU2oCysYJvjA14psH2%2F77mepvpdYfnweLL4iAXdAXiR5mAooI57xaVDPLqtS2u2cUo7%2BHokZbYx9krSelAhFbHhxUOv2CDMWlxvsEZrI3r5WrRI98VRId%2B6G3Dccr8DKgncuxyI4mt4aIs2z%2FsblknTAEAAA%3D%3D&config=H4sIAAAAAAAAA02OMQ7CMAxF7%2BK5A7CRFVa4g5WYipLEke1KRFXuTiKEyvaH9%2FT%2BBot6cBsUFCUZS2s2fIMDq4XUy7MYTBDIs6CxKDiTldoEJpj1wZKGFWlGX68%2F6gv9aTcyDGi42ygzWc%2BQng7Hc0%2B8iMolouodE%2B2ZxGGNNBrjUBc8p8R5UWjtA3yjCke%2FAAAA

Expected behavior

[Function: String] is output

Actual behavior

[Function: Object] is output

Version

@swc/core: 1.2.133

Additional context

Used #2703 as a reference.

[kdy1]

This requires typesystem

[kdy1]

Closing as the Closing as the stc is now abandoned. #571 (comment)

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.