fix: allow an undefined user id to be passed (#776)

Author: cjbell

.changeset/swift-papayas-design.md

@@ -0,0 +1,5 @@
+---
+"@knocklabs/client": patch
+---
+
+fix: ensure that user.id can be undefined

packages/client/src/knock.ts

@@ -239,7 +239,7 @@ class Knock {
       return userIdOrUserWithProperties.id;
     }
 
-    throw new Error("`user` object must contain an `id` property");
+    return undefined;
   }
 }
 

packages/client/test/knock.test.ts

@@ -186,12 +186,14 @@ describe("Knock Client", () => {
       expect(identify).toHaveBeenCalledWith({ name: "John Doe" });
     });
 
-    test("throws error when user object does not contain an `id` property", () => {
+    test("does not identify user when user object does not contain an `id` property", () => {
       const knock = new Knock("pk_test_12345");
+      const identify = vi.spyOn(knock.user, "identify");
+
       // @ts-expect-error - we want to test the error case
-      expect(() => knock.authenticate({ name: "John Doe" })).toThrowError(
-        "`user` object must contain an `id` property",
-      );
+      knock.authenticate({ name: "John Doe" });
+
+      expect(identify).not.toHaveBeenCalled();
     });
   });