i18n strings in artifacts from -G throw errors when run through -A

[connorjclark]

Provide the steps to reproduce

node lighthouse-cli https://www.example.com -G and when Chrome pops up immediately move it out of focus to force NO_FCP

node lighthouse-cli https://www.example.com -A --view

What is the current behavior?

Runtime error encountered: Cannot read property 'icuMessage' of undefined
TypeError: Cannot read property 'icuMessage' of undefined
    at _resolveIcuMessageInstanceId (/Users/cjamcl/src/lighthouse/lighthouse-core/lib/i18n/i18n.js:300:24)
    at replaceInObject (/Users/cjamcl/src/lighthouse/lighthouse-core/lib/i18n/i18n.js:327:55)
    at replaceInObject (/Users/cjamcl/src/lighthouse/lighthouse-core/lib/i18n/i18n.js:340:9)
    at Object.replaceIcuMessageInstanceIds (/Users/cjamcl/src/lighthouse/lighthouse-core/lib/i18n/i18n.js:347:3)
    at Function.run (/Users/cjamcl/src/lighthouse/lighthouse-core/runner.js:155:39)
    at process._tickCallback (internal/process/next_tick.js:68:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:745:11)
    at startup (internal/bootstrap/node.js:282:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:743:3)

What is the expected behavior?

no error.

[brendankenny]

ICU replacement errors for -G w/ NO_FCP
Runtime error encountered: Cannot read property 'icuMessage' of undefined

unfortunately not fixed by #9397 like I initially thought it would be. This string is in LighthouseRunWarnings in the artifacts. At the end of then running LH with -A, the localization step tries to look up the string but it's not in _icuMessageInstanceMap because the str() call happened in the gather phase, not the current run.

However, there's a deeper problem with fixing: even if we did a lookup based on the id, for strings with replacement like the NO_FCP warning (badTraceRecording), the replacement values are long gone, so the string can't be reconstructed anyways.

We could

• do a replacer/reviver for i18n strings in artifacts
• or some kind of icuMessagePaths but for artifacts and swap upon loading them
• or come up with a new icuMessage format

we can call this medium priority. This is the only instance I know of after #9397 handles LHErrors, and only happens if you run just -G and then just -A (so basically just us), but it could happen more if we want to e.g. pipe localized strings from gatherers all the way to audits.

[brendankenny]

fixed in #10630