Allow optional chaining

Today if you use [optional chaining](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining) the linting rules show a red thing constantly b/c it may not have that key, but that's what optional chaining is for.

Start by locating the repository's linting rules and the checks that report errors for optional chaining. Confirm how the linked JavaScript optional-chaining syntax is currently handled; done means valid optional chaining no longer produces the reported lint warning while other linting behavior remains intact.

Written by the indexing model from the issue text.