2066877 - L10nCache.add() throws on an unknown Fluent ID instead of reporting it

Status: RESOLVED FIXED

(Firefox :: Address Bar, task, P3)

Description

[Dão Gottwald [:dao]]

Filing as a good first bug to learn workflows.

L10nCache.add() in browser/components/urlbar/content/L10nCache.mjs guards against l10n.formatMessages() returning an empty array, but not against it resolving with a null message, which is what happens when the requested Fluent ID does not exist. The messages[0].value access then throws TypeError: can't access property "value", messages[0] is null, and because add() is awaited while building the urlbar result menu, one unknown ID leaves the whole menu empty instead of dropping a single item. Bug 2066758 is an instance of that.

The fix is to treat a null message the same way the empty array is treated: report it with console.error and return.

Link to the code:
https://searchfox.org/firefox-main/rev/2aa0bcf95c98681376e30d6a9aa4df2b27885abc/browser/components/urlbar/content/L10nCache.mjs#122-131

A unit test belongs in browser/components/urlbar/tests/unit/test_l10nCache.js, which builds a Localization over a mock file source via its initL10n() helper: adding an ID that the mock source does not define should leave the cache empty rather than reject.

To verify the fix:

./mach test browser/components/urlbar/tests/unit/test_l10nCache.js

Tutorial to contribute:
https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
https://firefox-source-docs.mozilla.org/contributing/stack_quickref.html

Please don't ask for the bug to be assigned. It will be automatically assigned to the first patch.

Comment 1

[Raúl]

Attachment: Bug 2066877 - Report and ignore null messages in L10nCache. r=#urlbar-reviewers

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/ea0563a508ae
https://hg.mozilla.org/integration/autoland/rev/c57e8a70d96b
Report and ignore null messages in L10nCache. r=adw

Comment 3

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/c57e8a70d96b