Noticed this warning in the console on test.wikipedia.org (after saving an edit) while testing a patch for T193570 (probably unrelated).
```counterexample
Exception in load-callback in module schema.SaveTiming:
> Error: Module "ext.navigationTiming.rumSpeedIndex" is not loaded.
at require (load.php?...:171)
at getPaintTiming (<anonymous>:206:555)
at getNavTiming (<anonymous>:207:578)
at emitSaveTiming (<anonymous>:209:709)
```
Looks like we forgot about the second call-path to `getNavTiming()` when adding rumSpeedIndex, namely from `emitSaveTiming`, which while being called after the load starts for `preloadedModules`, does not wait for it (and shouldn't need to)
Its report rate dropped by about 30%. I guess the reason it didn't drop further is because depends on a particular cache state, in which the unrelated load for `preloadedModules` remains unresolved (cache miss or some version change), but `schema.SaveTiming` is cache-hit for emitSaveTiming. Within a warm cache scenario, this does indeed seem likely given that schema hasn't changed in years, whereas our other modules have.
<https://graphite.wikimedia.org/render?width=1200&height=600&from=20180423&until=20180430&target=scale(mw.performance.save.sample_rate,60)>
| {F17606908}
|--
| From 150/min to 100/min
|---