[pkg/sync] Closer.Close() returns error

[ggwpez]

Location

[pkg/sync] Closer.Close() error function.

Problem

The Close function can only return one error; alreadyClosedError. In case it was not already closed, it just returns nil.

Proposal

Since it only returns one error type, we could also use a success bool here for brevity.
This would also make the error handling shorter since we often log errors when handling them.

[ggwpez]

We talked about that this is a convention in go, and that the error is ought to be ignored 🤦