Unhandled rejection check causes errors in Firefox

• Bluebird 3.7.0
• Firefox 71 (Nightly)

I recently upgraded from Bluebird 3.5.5 to 3.7.0, which happens to pull in the unhandled rejection handling from https://github.com/petkaantonov/bluebird/commit/60ef7a0e23fd320a11281f67c64a39ff95612ce9 (first added in 3.6.0).

The path which adds an iframe, grabs setTimeout from it, then removes it from the document does not appear to work in Firefox 71. Instead, calling this setTimeout fails with an NS_ERROR_NOT_INITIALIZED exception.

(As an aside, I am curious why you want to pull setTimeout from a throwaway frame like this… Why not just use the main document?)

For now, I will revert back to 3.5.5.

[MattiasBuelens]

As described here, Bluebird creates an iframe, takes its setTimeout function and then removes the iframe from the DOM. It then uses that function to schedule checks for unhandled rejections.

I suspect that Firefox destroys the window of the iframe when it’s removed from the DOM, and as such the setTimeout function becomes invalid.

Can’t we capture the original value of setTimeout while Bluebird is loading, and always use that inside deferUnhandledRejectionCheck? That way, Bluebird would not be affected by a test framework replacing the global setTimeout afterwards. It would also be much simpler, without needing platform-specific specializations.

[jaapz]

I was experiencing this bug as well and the newly released version 3.7.2 fixed it for me.