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Rule priority, scope & exceptions
Use this to align rules with the senior-level structure (P0/P1/P2, scope, exceptions/tradeoffs).
backend ruleP2universalStack: TypeScript
api-designnull-handlinggraceful-degradation
Return the best available data instead of null when you can
Preserve valid partial data using an explicit domain contract; never fabricate a value merely to avoid null.
PR: hegnar-user-ws · org-mining-hist-2026-06Created: Jun 18, 2026
Bad example
Old codetypescript
| 1 | const market = marketplaces.find((m) => m.insref === instrument.marketplace); |
| 2 | if (!market) { |
| 3 | return null; |
| 4 | } |
Explanation (EN)
Discarding independently valid data may unnecessarily remove useful information, but a fallback must remain truthful.
Objašnjenje (HR)
Good example
New codetypescript
| 1 | const market = marketplaces.find((m) => m.insref === instrument.marketplace); |
| 2 | if (!market) { |
| 3 | return lastUpdated; // still return useful info |
| 4 | } |
Explanation (EN)
Objašnjenje (HR)
Notes (EN)
Return partial or fallback data only when the domain defines its meaning and consumers can distinguish uncertainty where it matters.
Exceptions / Tradeoffs (EN)
Do not replace an unknown timestamp, financial value or required fact with now or another convenient value. Preserve null or an explicit unavailable result when no valid substitute exists.