Add support for non async hooks

Signed-off-by: Johan Haals <johan.haals@gmail.com>

packages/backend-app-api/src/services/implementations/lifecycleService.ts

@@ -39,8 +39,8 @@ class BackendLifecycleImpl {
     this.logger.info(`Running ${this.#shutdownTasks.length} shutdown tasks...`);
     await Promise.all(
       this.#shutdownTasks.map(hook =>
-        hook
-          .fn()
+        Promise.resolve()
+          .then(() => hook.fn())
           .catch(e => {
             this.logger.error(
               `Shutdown hook registered by plugin '${hook.pluginId}' failed with: ${e}`,

packages/backend-plugin-api/src/services/definitions/lifecycleServiceRef.ts

@@ -20,7 +20,7 @@ import { createServiceRef } from '../system/types';
  * @public
  **/
 export type BackendLifecycleShutdownHook = {
-  fn: () => Promise<void>;
+  fn: () => void | Promise<void>;
 };
 
 /**