Warn if app-backend can't start-up because missing dir

.changeset/brave-rats-obey.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-app-backend': patch
+---
+
+Warn if the app-backend can't start-up because the static directory that should be served is unavailable.

plugins/app-backend/src/service/router.ts

@@ -21,6 +21,7 @@ import { Logger } from 'winston';
 import { notFoundHandler, resolvePackagePath } from '@backstage/backend-common';
 import { Config } from '@backstage/config';
 import { injectConfig, readConfigs } from '../lib/config';
+import fs from 'fs-extra';
 
 export interface RouterOptions {
   config: Config;
@@ -35,9 +36,18 @@ export async function createRouter(
   const { config, logger, appPackageName, staticFallbackHandler } = options;
 
   const appDistDir = resolvePackagePath(appPackageName, 'dist');
-  logger.info(`Serving static app content from ${appDistDir}`);
   const staticDir = resolvePath(appDistDir, 'static');
 
+  if (!(await fs.pathExists(staticDir))) {
+    logger.warn(
+      `Can't serve static app content from ${staticDir}, directory doesn't exist`,
+    );
+
+    return Router();
+  }
+
+  logger.info(`Serving static app content from ${appDistDir}`);
+
   const appConfigs = await readConfigs({
     config,
     appDistDir,