Fix infinite loop when hoisting cyclic dependencies

[yungsters]

Fixes a bug that causes yarn to infinite loop (and subsequently fail by running out of memory).

This makes yarn add @bluejay/[email protected] succeed, a cyclic dependency that currently breaks yarn and was originally reported in #6279.

Test Plan

$ yarn
$ yarn test
$ yarn build

Verified this now succeeds:

$ yarn add @bluejay/[email protected]

[augustovicente]

Suggested change

	if (parent != null && parent.previousPatterns.has(pattern)) {
	return null;
	}
	if (parent?.previousPatterns?.has(pattern)) {
	return null;
	}

[augustovicente]

Set constructor works fine if the argument is undefined. It will create an empty Set, so we can skip this validation.

Suggested change

	info.previousPatterns = new Set(parent == null ? [] : parent.previousPatterns).add(pattern);
	info.previousPatterns = new Set(parent?.previousPatterns).add(pattern);