The union of error codes in E's static type — not the full enum of the class, but exactly the codes this value may carry. Distributes over unions, so XError<A> | XError<B> and XError<A | B> both give A | B.
E
XError<A> | XError<B>
XError<A | B>
A | B
The union of error codes in
E's static type — not the full enum of the class, but exactly the codes this value may carry. Distributes over unions, soXError<A> | XError<B>andXError<A | B>both giveA | B.