some unexpected unknowns in O.Assign and O.MergeAll

[mesqueeb]

🐞 Bug Report

"ts-toolbelt": "^9.6.0"
"typescript": "^4.4.4"

and my tsconfig

{
  "compilerOptions": {
    "baseUrl": ".",
    "lib": ["ES2015", "ES2016", "ES2017", "ES2018", "ES2019", "ES2020"],
    "strictNullChecks": true,
    "strict": true,
    "isolatedModules": true,
    "esModuleInterop": true,
    "moduleResolution": "node",
    "declaration": true,
    "declarationDir": "./types/"
  }
}

Describe the bug

I see some types that I'd not expect from reading the docs on the utils:

Reproduce the bug

export type MyType = {
  strArr: string[]
}

type t1 = O.Assign<MyType, [Partial<MyType>, { a?: number }, { b: number }], 'deep'>
// expect
// {
//   b: number;
//   a?: number;
//   strArr: string[];
// }
// get
// {
//   b: number;
//   a?: unknown;
//   strArr: unknown;
// }

type t2 = O.MergeAll<MyType, [Partial<MyType>, { a?: number }, { b: number }], 'deep'>
// expect
// {
//   strArr: string[];
//   a?: number;
//   b: number;
// }
// get
// {
//   strArr: string[];
//   a?: unknown;
//   b: number;
// }

edit: fixed some typos in the expected/gotten types