util-array-object-or-both^5.2.1

`ast-delete-key/deleteKey(): [THROW_ID_01] The variable "opts.only" was customised to an unrecognised value: sweetcarrots. Please check it against the API documentation.`;

import type { ArrayObjectOrBoth, Opts } from "util-array-object-or-both";

// require this library:
import { arrObjOrBoth } from 'util-array-object-or-both';
// and friends:
import clone from 'lodash.clonedeep'
import {checkTypes} from 'check-types-mini'
// let's say you have a function:
function myFunc (input, opts) {
  // now you want to check your options object, is it still valid after users have laid their sticky paws on it:
  // define defaults:
  let defaults = {
    lalala: null,
    only: 'object' // <<< this is the value to validate, is it `array`|`object`|`any`
  };
  // clone the defaults to safeguard it, and then, object-assign onto defaults.
  // basically you fill missing values with default-ones
  const resolvedOpts = {...defaults, ...opts};
  // now, use "check-types-mini" to validate the types:
  checkTypes(resolvedOpts, defaults,
    {
      // give a meaningful message in case it throws,
      // customise the library `check-types-mini`:
      msg: 'my-library/myPrecious(): [THROW_ID_01]',
      optsVarName: 'opts',
      schema: {
        lalala: ['null', 'string'],
        only: ['null', 'string']
      }
    }
  )
  // by this point, opts.only is guaranteed to be either `null` or `string`.
  // if it's a `string`, let's validate is its values among accepted-ones:
  resolvedOpts.only = arrObjOrBoth(opts.only, {
    msg: 'my-library/myPrecious(): [THROW_ID_02]',
    optsVarName: 'opts.only'
  })
  // now it's guaranteed to be either falsy (undefined or null) OR:
  //   - `object`
  //   - `array`
  //   - `any`

  // now you can use `opts.only` in your function safely.
  ...
  // rest of the function...
}