option-t/esm/plain_result/operators/map_err_async.js

A toolkit of Nullable/Option/Result type implementation in ECMAScript. Their APIs are inspired by Rust's `Option<T>` and `Result<T, E>`.

import { createErr, isOk } from '../core/result.js';
import { unsafeUnwrapValueInErrWithoutAnyCheck } from '../internal/intrinsics_unsafe.js';
/**
 *  Maps a `Result<T, E>` to `Result<T, F>` by applying a _transformer_ function `mapFn<E, F>`
 *  to an contained `Err(E)` value, leaving an `Ok(T)` value untouched.
 *
 *  This function can be used to pass through a successful result while handling an error.
 */
export async function mapErrAsyncForResult(input, transformer) {
    if (isOk(input)) {
        return input;
    }
    const err = unsafeUnwrapValueInErrWithoutAnyCheck(input);
    const e = await transformer(err);
    const result = createErr(e);
    return result;
}