See bug 1684190 for context.

When data-l10n-id, setAttributes, or formatValues or similar is used with a fluent message that includes a $variable, and the data-l10n-args and/or args part of the API call does not include that variable (Note: different from just setting it to "") then fluent should assert on debug builds, and/or in automation for opt builds, so we catch missing variable issues like the one in bug 1684190 immediately.

I agree.

In bug 1613705 with the move to Rust I'm improving our errors wrangling from Fluent to surface, and will add ability to crash in automation at least.

What would it take to fix this / get this prioritized?

Erik, do you think this could/should be fixed by adding an appropriate debug_assert! to fluent-rs, or should we handle this at a higher level?

I think it would make sense to add debug_assert! calls upstream, but I want to double check with people like Zibi who originally designed Fluent-rs and may have a better idea of how that may affect other users.

I've opened an issue of it on GitHub.

https://github.com/projectfluent/fluent-rs/issues/265

I'm leaving this NI open to make sure I follow up on this.

Zibi mentioned this: https://searchfox.org/mozilla-central/rev/3c194fa1d6f339036d2ec9516bd310c6ad612859/intl/l10n/Localization.h#45

I haven't looked at the specific bindings myself in our codebase, but it seems like it should be handled in our own usage of fluent-rs rather than in upstream.

I don't think these are actual bugs, as these are crashing due to
missing dynamic data. I felt it was fine to add empty strings here.

Depends on D161996

Backed out for causing Xpcshell failures at test_l10nCache.js.

Backout link: https://hg.mozilla.org/integration/autoland/rev/1e556c93a8c89b148ab70183ed37dc9e6c97d97e

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=c05d7c567c19a5801faf1995bf050cbb6dd79164&selectedTaskRun=CSjL2av3SAyOEhmjFbxtMg.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=397235068&repo=autoland&lineNumber=3646

Depends on D162336

And this is also perma: https://treeherder.mozilla.org/logviewer?job_id=397245653&repo=autoland

Also toolkit/components/antitracking/test/browser/browser_urlQueryStringStripping_pbmode.js

Which is bug 1801716

Depends on D162597

https://hg.mozilla.org/mozilla-central/rev/7b60e053cb45
https://hg.mozilla.org/mozilla-central/rev/2ce6ad4ea83c
https://hg.mozilla.org/mozilla-central/rev/f69ffa081b91
https://hg.mozilla.org/mozilla-central/rev/8e10d2d72d9b