cars: import handles models without years, keeps roman numerals upper-case; don't cache an empty overview

scripts/cars-import.ts

@@ -17,6 +17,10 @@
 // Re-runnable: brands/models are upserted by slug (Dex numbers stay stable, new models get
 // the next number), models that vanished are deleted, variants are replaced.
 import postgres from 'postgres';
+
+const known = (xs: (number | null)[]) => xs.filter((x): x is number => x != null);
+const minOrNull = (xs: (number | null)[]) => (known(xs).length ? Math.min(...known(xs)) : null);
+const maxOrNull = (xs: (number | null)[]) => (known(xs).length ? Math.max(...known(xs)) : null);
 import { mkdir, readFile, writeFile } from 'node:fs/promises';
 import { join } from 'node:path';
 
@@ -333,7 +337,7 @@ const TRIM_WORDS = new Set(
 	INJECTION ETECH PLUGIN HYBRID4 XDRIVE SDRIVE EDRIVE QUATTRO MOTION MATIC AWD WD X`.split(/\s+/)
 );
 const KEEP_UPPER = new Set(
-	'GTI GTD GTE GTX GT AMG SUV MPV RS ST EV BEV PHEV TDI TSI SRT SS SVR SVT XL XLT CC SW TT GTS GTV RV CR-V HR-V EQA EQB EQC EQE EQS EQV EQT UX NX RX LX GX IS ES LS LC RC'.split(
+	'GTI GTD GTE GTX GT AMG SUV MPV RS ST EV BEV PHEV TDI TSI SRT SS SVR SVT XL XLT CC SW TT GTS GTV RV CR-V HR-V EQA EQB EQC EQE EQS EQV EQT UX NX RX LX GX IS ES LS LC RC II III IV VI VII VIII IX XI XII'.split(
 		' '
 	)
 );
@@ -828,8 +832,8 @@ function build(src: Awaited<ReturnType<typeof loadSources>>, fuel: RdwFuel[]) {
 					.join(' ')
 					.toLowerCase()
 					.slice(0, 4000),
-				firstYear: Math.min(...years),
-				lastYear: Math.max(...years),
+				firstYear: years.length ? Math.min(...years) : null,
+				lastYear: years.length ? Math.max(...years) : null,
 				bodies,
 				sizeClasses: [...m.sizeClasses].sort(),
 				fuels,
@@ -881,8 +885,8 @@ function build(src: Awaited<ReturnType<typeof loadSources>>, fuel: RdwFuel[]) {
 			name,
 			country: COUNTRIES[b.key] ?? null,
 			nlCount: b.nlCount,
-			firstYear: Math.min(...models.map((m) => m.firstYear)),
-			lastYear: Math.max(...models.map((m) => m.lastYear)),
+			firstYear: minOrNull(models.map((m) => m.firstYear)),
+			lastYear: maxOrNull(models.map((m) => m.lastYear)),
 			sources: [...b.sources].sort(),
 			models
 		});

src/lib/server/cars.ts

@@ -132,7 +132,7 @@ export async function carOverview(): Promise<Overview> {
 			nlCars: Number(counts.nlCars)
 		}
 	};
-	overviewCache = { at: Date.now(), value };
+	if (value.stats.models) overviewCache = { at: Date.now(), value };
 	return value;
 }