fix(discover): Handle undefined saved query dataset

[sentry]

Addresses JAVASCRIPT-38Z5, a TypeError: can't access property "environment", e is undefined occurring on /explore/discover/homepage/.

The root cause was identified in static/app/views/discover/results.tsx within the checkEventView method. When getSavedQueryDataset returns a value that is not a key in DEFAULT_EVENT_VIEW_MAP (e.g., an unrecognized or missing dataset), the lookup DEFAULT_EVENT_VIEW_MAP[value] evaluates to undefined. This undefined value was then passed as the newQuery argument to EventView.fromNewQueryWithLocation.

Inside EventView.fromNewQueryWithLocation, an attempt to access newQuery.environment (line 415 in static/app/utils/discover/eventView.tsx) on an undefined newQuery object resulted in the reported TypeError.

This fix introduces a nullish coalescing operator (?? DEFAULT_EVENT_VIEW) at the point of the DEFAULT_EVENT_VIEW_MAP lookup in checkEventView. This ensures that if DEFAULT_EVENT_VIEW_MAP[value] is undefined, DEFAULT_EVENT_VIEW is used as a fallback, preventing undefined from being passed to EventView.fromNewQueryWithLocation and thus resolving the TypeError.

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

Fixes JAVASCRIPT-38Z5

_{This PR was automatically generated by Sentry. You can adjust this setting at any time.}

[github-actions]

📊 Type Coverage Diff

Metric	Before	After	Delta
Coverage	94.36%	94.36%	±0%
Typed	134,654	134,654	±0
Untyped	8,048	8,048	±0

🔍 1 new type safety issue introduced

Type assertions (as) (1 new)

File	Line	Detail
static/app/views/discover/results.tsx	444	as NewQuery — getSavedQueryWithDataset( DEFAULT_EVENT_VIEW_MAP[value] ?? DEFAULT_EVENT_VIEW )…

This is informational only and does not block the PR.