Navigation: inner navigate firing algorithm does not say what to do if invoking NavigationInterceptHandler throws

[ADKaster]

Step 33.2.1 of the inner navigate firing algorithm simply states:

Append the result of invoking handler with an empty arguments list to promisesList.

However, handler is an IDL callback, so invoking it, even if the return type is a Promise type, could throw. ... assuming my reading of https://webidl.spec.whatwg.org/#invoke-a-callback-function is correct.

Other parts of the HTML specification make sure to say that "invoke such and such callback, and if that throws, report the exception", pointing towards https://html.spec.whatwg.org/multipage/webappapis.html#report-the-exception

Are these steps not necessary as NavigationInterceptHandler is Promise<undefined> ()? Or do we need a "report the exception" step in 33.2 of the inner navigate firing algorithm?

[domenic]

Are these steps not necessary as NavigationInterceptHandler is Promise<undefined> ()?

That is correct. It is impossible for invoking a promise-returning callback to throw, as any exceptions are converted into rejected promises. See https://webidl.spec.whatwg.org/#invoke-a-callback-function step 11-14, which never allow an exception (abrupt completion) to escape.