fix: tolerate missing race cover image field

Reviewed-on: #32

backend/src/mappers/race.ts

@@ -66,7 +66,7 @@ export function rowToDto(row: RaceRow): RaceDto {
     distanceKm: parseFloat(row.distance_km),
     status: row.status,
     officialUrl: row.official_url,
-    coverImageUrl: row.cover_image_url,
+    coverImageUrl: row.cover_image_url ?? null,
     startTime: row.start_time,
     clusterSchedule: row.cluster_schedule,
     bibPickup: row.bib_pickup,

frontend/src/api/races.ts

@@ -10,6 +10,10 @@ function isNullableString(value: unknown): value is string | null {
   return value === null || typeof value === "string";
 }
 
+function isOptionalNullableString(value: unknown): value is string | null | undefined {
+  return value === undefined || isNullableString(value);
+}
+
 function normalizeRace(input: unknown): Race {
   const race = input as Partial<Race>;
 
@@ -23,7 +27,7 @@ function normalizeRace(input: unknown): Race {
       race?.status === "registered" ||
       race?.status === "completed") &&
     isNullableString(race?.officialUrl) &&
-    isNullableString(race?.coverImageUrl) &&
+    isOptionalNullableString(race?.coverImageUrl) &&
     isNullableString(race?.startTime) &&
     isNullableString(race?.clusterSchedule) &&
     isNullableString(race?.bibPickup) &&
@@ -49,7 +53,7 @@ function normalizeRace(input: unknown): Race {
     distanceKm: race.distanceKm,
     status: race.status,
     officialUrl: race.officialUrl,
-    coverImageUrl: race.coverImageUrl,
+    coverImageUrl: race.coverImageUrl ?? null,
     startTime: race.startTime,
     clusterSchedule: race.clusterSchedule,
     bibPickup: race.bibPickup,