prevents trim is not a function exception

packages/node/src/exposure/exposure.ts

@@ -29,11 +29,20 @@ export class Exposure {
   }
 
   public canonicalize(): string {
-    let canonical = `${this.user.user_id?.trim()} ${this.user.device_id?.trim()} `;
+    const userId =
+      this.user.user_id != null
+        ? String(this.user.user_id).trim()
+        : this.user.user_id;
+    const deviceId =
+      this.user.device_id != null
+        ? String(this.user.device_id).trim()
+        : this.user.device_id;
+    let canonical = `${userId} ${deviceId} `;
     for (const key of Object.keys(this.results).sort()) {
       const variant = this.results[key];
       if (variant?.key) {
-        canonical += key.trim() + ' ' + variant?.key?.trim() + ' ';
+        const variantKey = String(variant.key).trim();
+        canonical += key.trim() + ' ' + variantKey + ' ';
       }
     }
     return canonical;

packages/node/test/local/exposure/exposure-filter.test.ts

@@ -130,3 +130,29 @@ test('filter - ttl-based eviction', async () => {
   await sleep(950);
   expect(filter.shouldTrack(exposure2)).toEqual(false);
 });
+
+test('filter - non-string user_id should not throw', async () => {
+  // Simulate runtime scenario where user_id is a number (e.g., from untyped JS or JSON)
+  const user = { user_id: 12345 } as unknown as ExperimentUser;
+  const results = {
+    'flag-key-1': { key: 'on', value: 'on' },
+  };
+  const filter = new InMemoryExposureFilter(100);
+  const exposure = new Exposure(user, results);
+  // Should not throw TypeError: trim is not a function
+  expect(() => filter.shouldTrack(exposure)).not.toThrow();
+  expect(filter.shouldTrack(exposure)).toEqual(false); // Already tracked
+});
+
+test('filter - non-string device_id should not throw', async () => {
+  // Simulate runtime scenario where device_id is a number
+  const user = { device_id: 67890 } as unknown as ExperimentUser;
+  const results = {
+    'flag-key-1': { key: 'on', value: 'on' },
+  };
+  const filter = new InMemoryExposureFilter(100);
+  const exposure = new Exposure(user, results);
+  // Should not throw TypeError: trim is not a function
+  expect(() => filter.shouldTrack(exposure)).not.toThrow();
+  expect(filter.shouldTrack(exposure)).toEqual(false); // Already tracked
+});