feat(store): initial release (#279)

packages/store/test/errors.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from 'vitest';
+import { isStoreError, StoreError } from '../src/errors';
+
+describe('errors', () => {
+  describe('storeError', () => {
+    it('creates error with message', () => {
+      const error = new StoreError('test message');
+      expect(error.message).toBe('test message');
+      expect(error.name).toBe('StoreError');
+      expect(error).toBeInstanceOf(Error);
+    });
+
+    it('supports cause for error chaining', () => {
+      const cause = new Error('original error');
+      const error = new StoreError('wrapped error', { cause });
+      expect(error.message).toBe('wrapped error');
+      expect(error.cause).toBe(cause);
+    });
+  });
+
+  describe('type guard', () => {
+    it('isStoreError identifies store errors', () => {
+      expect(isStoreError(new StoreError('test'))).toBe(true);
+      expect(isStoreError(new Error('regular'))).toBe(false);
+      expect(isStoreError(null)).toBe(false);
+    });
+  });
+});