fix: stack account id throws error if not a string (#25134)

If the account id passed in as stack environment is not a string, then that leads to errors in some lookup functions. This PR is adding a type check for stack's account id and region. These are only allowed to be `string` datatype. 

Closes #21364

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: vinayak-kukreja

packages/aws-cdk-lib/core/lib/stack.ts

@@ -1358,6 +1358,15 @@ export class Stack extends Construct implements ITaggable {
     // in which Export/Fn::ImportValue would work is if the value are the same
     // between producer and consumer anyway, so we can just assume that they are).
     const containingAssembly = Stage.of(this);
+
+    if (env.account && typeof(env.account) !== 'string') {
+      throw new Error(`Account id of stack environment must be a 'string' but received '${typeof(env.account)}'`);
+    }
+
+    if (env.region && typeof(env.region) !== 'string') {
+      throw new Error(`Region of stack environment must be a 'string' but received '${typeof(env.region)}'`);
+    }
+
     const account = env.account ?? containingAssembly?.account ?? Aws.ACCOUNT_ID;
     const region = env.region ?? containingAssembly?.region ?? Aws.REGION;
 

packages/aws-cdk-lib/core/test/stack.test.ts

@@ -1,8 +1,8 @@
 import { testDeprecated } from '@aws-cdk/cdk-build-tools';
-import * as cxapi from '../../cx-api';
-import { Fact, RegionInfo } from '../../region-info';
 import { Construct, Node } from 'constructs';
 import { toCloudFormation } from './util';
+import * as cxapi from '../../cx-api';
+import { Fact, RegionInfo } from '../../region-info';
 import {
   App, CfnCondition, CfnInclude, CfnOutput, CfnParameter,
   CfnResource, Lazy, ScopedAws, Stack, validateString,
@@ -2071,6 +2071,40 @@ describe('stack', () => {
     stack.node.setContext(cxapi.BUNDLING_STACKS, []);
     expect(stack.bundlingRequired).toBe(false);
   });
+
+  test('account id passed in stack environment must be a string', () => {
+    // GIVEN
+    const envConfig: any = {
+      account: 11111111111,
+    };
+
+    // WHEN
+    const app = new App();
+
+    // THEN
+    expect(() => {
+      new Stack(app, 'Stack', {
+        env: envConfig,
+      });
+    }).toThrowError('Account id of stack environment must be a \'string\' but received \'number\'');
+  });
+
+  test('region passed in stack environment must be a string', () => {
+    // GIVEN
+    const envConfig: any = {
+      region: 2,
+    };
+
+    // WHEN
+    const app = new App();
+
+    // THEN
+    expect(() => {
+      new Stack(app, 'Stack', {
+        env: envConfig,
+      });
+    }).toThrowError('Region of stack environment must be a \'string\' but received \'number\'');
+  });
 });
 
 describe('permissions boundary', () => {