unhandledrejectionhandler called multiple times for same error

[cdietze]

When chaining promises using then the behavior between Chrome's native onunhandledrejectionhandler and core-js' implementation differ.

Promise.reject(43).then(x => x); will invoke the handler twice in core-js and once in Chrome.
I suppose Chrome's behavior is correct.

demo

[zloirock]

In this example, we have 2 promises, so triggered 2 events. Need to check HTML spec for confirming which behaviour is correct.

[benjamingr]

@zloirock the ES spec is ambiguous about this

[zloirock]

Fixed in core-js@2.5.3.