backend-app-api: improved error messaging when default factory loaders throw

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/backend-app-api/src/wiring/ServiceRegistry.test.ts

@@ -276,4 +276,20 @@ describe('ServiceRegistry', () => {
       "Failed to instantiate service '1' for 'catalog' because the factory function threw an error, Error: error in plugin catalog",
     );
   });
+
+  it('should decorate error messages thrown by default factory loaders', async () => {
+    const ref = createServiceRef<string>({
+      id: '1',
+      defaultFactory() {
+        throw new Error('default factory error');
+      },
+    });
+
+    const registry = new ServiceRegistry([]);
+    const factory = registry.get(ref)!;
+
+    await expect(factory('catalog')).rejects.toThrow(
+      "Failed to instantiate service '1' because the default factory loader threw an error, Error: default factory error",
+    );
+  });
 });

packages/backend-app-api/src/wiring/ServiceRegistry.ts

@@ -48,11 +48,21 @@ export class ServiceRegistry {
       if (!factory) {
         let loadedFactory = this.#loadedDefaultFactories.get(defaultFactory!);
         if (!loadedFactory) {
-          loadedFactory = defaultFactory!(ref) as Promise<ServiceFactory>;
+          loadedFactory = Promise.resolve().then(
+            () => defaultFactory!(ref) as Promise<ServiceFactory>,
+          );
           this.#loadedDefaultFactories.set(defaultFactory!, loadedFactory);
         }
         // NOTE: This await is safe as long as #providedFactories is not mutated.
-        factory = await loadedFactory;
+        factory = await loadedFactory.catch(error => {
+          throw new Error(
+            `Failed to instantiate service '${
+              ref.id
+            }' because the default factory loader threw an error, ${stringifyError(
+              error,
+            )}`,
+          );
+        });
       }
 
       let implementation = this.#implementations.get(factory);