eql({}, null) throws WeakMap key error

[STRML]

Simple reproduction:

$ node
> const eql = require('deep-eql')
undefined
> eql({}, null)
TypeError: Invalid value used as weak map key
    at WeakMap.set (native)
    at memoizeSet (/Users/samuelreed/git/forks/ajv/node_modules/deep-eql/index.js:92:17)
    at extensiveDeepEqual (/Users/samuelreed/git/forks/ajv/node_modules/deep-eql/index.js:175:5)
    at deepEqual (/Users/samuelreed/git/forks/ajv/node_modules/deep-eql/index.js:141:10)
    at repl:1:1
    at sigintHandlersWrap (vm.js:22:35)
    at sigintHandlersWrap (vm.js:96:12)
    at ContextifyScript.Script.runInThisContext (vm.js:21:12)
    at REPLServer.defaultEval (repl.js:313:29)
    at bound (domain.js:280:14)
$ node --version
v6.9.1

[STRML]

Seems this could be fixed by checking both sides in the entry point:

  // Primitives/null/undefined can be checked for referential equality; returning early
  if (
    typeof leftHandOperand !== 'object' ||
    leftHandOperand === null ||
    leftHandOperand === undefined || // eslint-disable-line no-undefined
    typeof rightHandOperand !== 'object' ||
    rightHandOperand === null ||
    rightHandOperand === undefined // eslint-disable-line no-undefined
  ) {
    return leftHandOperand === rightHandOperand;
  }

Any reason not to?

[keithamus]

Thanks for the issue @STRML, also thanks for the proposed solution. Seems completely reasonable to me, if you'd like to write a PR with your proposed solution and some tests, that'd be aaawwwesome! 😝

---

Edit: nvm, I see you have made one! Thanks, I'll review it 😄

[lucasfcosta]

Thanks for your work @STRML! Great job 😄