`Promise.race` implementation changes behavior when used with non-promises

[aaemnnosttv]

Description

When the browser agent is loaded, Promise.race behaves differently when called with a non-promise.

This is a valid use of the function and can be used to inspect the status of a promise as documented here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/race#using_promise.race_to_detect_the_status_of_a_promise

Using this technique with the browser agent loaded results in Promises always evaluating to be pending, even when they are fulfilled.

This is easily testable in the browser as can be seen below.

Steps to Reproduce

When NRBA is loaded, Promise.race returns the first non-promise, even when a resolved promise is before it.

Expected Behavior

Promise.race should return the first fulfilled promise, even if followed by a non-promise.

A non-promise can still "beat" a promise in the race though. Essentially, resolved promises should be equal with non-promises, with the first one in the list winning.

Relevant Logs / Console output

See above

Your Environment

• Google Chrome Version 131.0.6778.265 (Official Build) (x86_64)
• MacOS 15.2
• Browser agent version 1.128.2
• APM language and version, if applicable (e.g., Dotnet 10.2.0), and auto|manual

Additional context

[workato-integration]

https://new-relic.atlassian.net/browse/NR-357533

[metal-messiah]

Thanks for reporting this! We are working on prioritizing this issue and hope to remedy this shortly.

[metal-messiah]

@aaemnnosttv Would you be able to supply a little more information regarding this issue? Are you utilizing any other 1st or 3rd party libraries that wrap the promise object? If so, which between that library and NR is loaded on the page first?

In local testing, I was not able to replicate the behavior on a page with New Relic browser agent as the only library, so I would like to understand if the interaction between two libraries wrapping the Promise object may be contributing to the behavior.

[workato-integration]

All attempts at reproducing this issue failed, or not enough information was available to reproduce the issue. Reading the code produces no clues as to why this behavior would occur. If more information appears later, please reopen the issue.

[cwli24]

@metal-messiah I had repro this in Chrome btw. Was playing around with the wrapping but didn't figure out way to correct it.