[TypeScript] TS error when declaring array path with { type: [{ type: String }] }

[thiagokisaki]

Do you want to request a feature or report a bug?
Report a bug.

What is the current behavior?
Currently, declaring an array path with { type: [{ type: String }] } causes a TS error.

If the current behavior is a bug, please provide the steps to reproduce.

import { Schema } from 'mongoose';

interface IProduct {
  keywords: string[];
}

const productSchema = new Schema<IProduct>({
  keywords: {
    type: [
      {
        type: String, // error in this line
        trim: true,
        lowercase: true,
        required: true,
      },
    ],
    required: true,
  },
});

TS error:

Type '{ type: { type: StringConstructor; trim: true; lowercase: true; required: true; }[]; required: true; }' is not assignable to type 'SchemaDefinitionProperty<string[]>'.
  Types of property 'type' are incompatible.
    Type '{ type: StringConstructor; trim: true; lowercase: true; required: true; }[]' is not assignable to type 'AnyArray<"string" | StringConstructor | "String" | typeof String>'.
      Type '{ type: StringConstructor; trim: true; lowercase: true; required: true; }[]' is not assignable to type '("string" | StringConstructor | "String" | typeof String)[]'.
        Type '{ type: StringConstructor; trim: true; lowercase: true; required: true; }' is not assignable to type '"string" | StringConstructor | "String" | typeof String'.
          Object literal may only specify known properties, and 'type' does not exist in type 'StringConstructor | typeof String'.ts(2322)

tsconfig.json:

{
  "compilerOptions": {
    "target": "es6",
    "rootDir": "src",
    "outDir": "dist",
    "baseUrl": "src",
    "paths": {
      "@/*": ["*"]
    },
    "module": "commonjs",
    "esModuleInterop": true,
    "strict": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src/**/*"],
}

What is the expected behavior?
No TypeScript error.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node.js: v14.17.3
Mongoose: v6.0.6
TypeScript: v4.4.3
MongoDB: irrelevant

[vkarpov15]

Fixed, fix will be in 6.0.8 👍