feat: emit errors as part of fetchFromMultipleSources

src/libs/fetchFromMultipleSources.ts

@@ -8,29 +8,43 @@ type OptionalArgs<T> =
       fetchFromCache?: undefined;
     };
 
+interface FetchFromMultipleSourcesResult<T> {
+  result: T | null;
+  errors: (Error | string | undefined)[] | null;
+}
+
 export async function fetchFromMultipleSources<T>(
   fetchPromises: (() => Promise<T | null | undefined>)[],
   args?: OptionalArgs<T>,
-) {
+): Promise<FetchFromMultipleSourcesResult<T>> {
   let result = await args?.fetchFromCache?.();
   if (result) {
-    return result;
+    return { result, errors: null };
   }
 
   if (fetchPromises.length === 0) {
     throw new Error("fetchPromises cannot be empty");
   }
 
-  for (const promise of fetchPromises) {
+  let errors: Record<number, Error> = {};
+  for (let i = 0; i < fetchPromises.length; i++) {
+    const promise = fetchPromises[i];
     try {
       result = await promise();
       if (result) break;
-    } catch (e) {}
+    } catch (e) {
+      errors[i] = e as Error;
+    }
   }
 
   if (args?.saveInCache && result) {
     await args.saveInCache(result);
   }
 
-  return result ?? null;
+  result = result ?? null;
+  return {
+    result,
+    errors:
+      !result && Object.keys(errors).length > 0 ? Object.values(errors) : null,
+  };
 }