Bug report

Optional array values are seemingly required.

Code snippet that reproduces the problem

Array with only one optional value: https://phpstan.org/r/8473da76-2e56-4c54-8c95-759431dbdfde

Array with a required and an optional value: https://phpstan.org/r/34641f8c-a839-43d2-a2ea-bf87638c24cc

Expected output

An array shape with optional values may have them missing.