Add @template-covariant to error on Result Interface

[TheDevick]

Hello!
I have a project where I have:
src/Http/Exceptions/ApiException.php
src/Http/Exceptions/ApiNotFoundException.php

Where ApiNotFound extends ApiException.

In a method, like:

class BookService
{
    /*
     * @return ResultInterface<Book, ApiException>
     */
    public function create(int $authorId, string $name, string $content): ResultInterface<Book, ApiException>
    {
        $author = ...

        if(!$author) // Author not found
        {
            return new Err(new ApiNotFoundException());
        }

        // ...
    }
}

Psalm tells me:

ERROR: InvalidReturnType - src/Service/BookService.php - The declared return type 'NeverThrow\ResultInterface<App\Entity\Book, App\Http\Exception\ApiException>' for App\Service\BookService::create is incorrect, got 'NeverThrow\Err<App\Http\Exception\ApiException>|NeverThrow\Err<App\Http\Exception\NotFoundException>|NeverThrow\Ok<App\Entity\Book>' (see https://psalm.dev/011) * @return ResultInterface<Book, ApiException>

ERROR: InvalidReturnStatement - src/Service/BookService.php - The inferred type 'NeverThrow\Err<App\Http\Exception\NotFoundException>' does not match the declared return type 'NeverThrow\ResultInterface<App\Entity\Book, App\Http\Exception\ApiException>' for Appsrc/Service/BookService::create (see https://psalm.dev/128) return new Err(new NotFoundException('Author not found')));

Solutions

Simply change the template from the error from Template to Template Covariant