Handle case when AWS region is configured as blank string (#2206)

.changeset/short-dryers-tell.md

@@ -0,0 +1,5 @@
+---
+'@aws-amplify/backend-cli': patch
+---
+
+Handle case when AWS region is configured as blank string

packages/cli/src/command_middleware.test.ts

@@ -122,6 +122,19 @@ void describe('commandMiddleware', () => {
         }
       });
 
+      void it('throws error if region is blank', async () => {
+        process.env.AWS_REGION = '';
+        delete process.env.AWS_DEFAULT_REGION;
+        try {
+          await commandMiddleware.ensureAwsCredentialAndRegion(
+            {} as ArgumentsCamelCase<{ profile: string | undefined }>
+          );
+          assert.fail('expect to throw error');
+        } catch (err) {
+          assert.match((err as Error).message, /The AWS region is blank/);
+        }
+      });
+
       void it('throws error if a profile is provided and no other credential providers', async () => {
         try {
           await commandMiddleware.ensureAwsCredentialAndRegion({

packages/cli/src/command_middleware.ts

@@ -60,8 +60,9 @@ export class CommandMiddleware {
     }
 
     // Check region.
+    let region: string | undefined = undefined;
     try {
-      await loadConfig(NODE_REGION_CONFIG_OPTIONS, {
+      region = await loadConfig(NODE_REGION_CONFIG_OPTIONS, {
         ignoreCache: true,
       })();
     } catch (err) {
@@ -77,6 +78,13 @@ export class CommandMiddleware {
         err as Error
       );
     }
+    if (!region.trim()) {
+      throw new AmplifyUserError('InvalidCredentialError', {
+        message: 'The AWS region is blank',
+        resolution:
+          'Ensure that a valid AWS region is provided in profile configuration or AWS_REGION environment variable.',
+      });
+    }
   };
 
   /**