2032387 - Don't use properties but the prototype chain for the "isWebDriverError()"

Status: RESOLVED FIXED

(Remote Protocol :: Agent, defect, P3)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Recently while working on bug 2031596 I noticed that a platform bug caused an error to be thrown which had the same name (UnknownError) as one of our known WebDriver Errors. As such the check that we run before serializing an error via isWebDriverError() returned true and caused the toJSON() method to be called which only exists for WebDriver errors:

https://searchfox.org/firefox-main/rev/662d18616bbb2da4c5a8758da50fc9d591d18c19/remote/shared/webdriver/Errors.sys.mjs#120-125

Given that this could be always the case when a fake object has similar properties and values we should not rely on them but find a better way to identify errors that are based on the WebDriver error type. Given that we cannot use instanceof we could use the actual prototype chain to check for a base WebDriverError entry. For the case above it works just fine.

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Here a try build for this change:
https://treeherder.mozilla.org/jobs?repo=try&landoInstance=lando-prod-2025&landoCommitID=36283

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Attachment: Bug 2032387 - [remote] Properly detect errors of type WebDriver error.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/d1e252ecae8f
https://hg.mozilla.org/integration/autoland/rev/160f7812b2d6
[remote] Properly detect errors of type WebDriver error. r=Sasha

Comment 4

[amarc]

https://hg.mozilla.org/mozilla-central/rev/160f7812b2d6