Fix addAction crash when called without optional attributes (#218)

## Summary
- `addAction(name)` crashes when the optional `attributes` argument is omitted because `span.setAttributes(undefined)` calls `Object.keys()` on `undefined` internally
- Guard the `setAttributes` call so it only runs when `attributes` is defined
- Add tests covering both cases (with and without attributes)

## Test plan
- [ ] Existing unit tests pass
- [ ] New test: `addAction('name')` without attributes does not throw and produces a span
- [ ] New test: `addAction('name', { key: 'value' })` produces a span with the expected attribute

Author: matsilva

.changeset/fix-add-action-optional-attrs.md

@@ -0,0 +1,5 @@
+---
+'@hyperdx/otel-web': patch
+---
+
+Fix addAction crash when called without optional attributes argument

packages/otel-web/src/index.ts

@@ -705,7 +705,9 @@ export const Rum: RumOtelWebType = {
     const now = Date.now();
     const tracer = this.provider.getTracer('custom-action');
     const span = tracer.startSpan(name, { startTime: now });
-    span.setAttributes(attributes);
+    if (attributes) {
+      span.setAttributes(attributes);
+    }
     span.end(now);
   },
 

packages/otel-web/test/SplunkOtelWeb.test.ts

@@ -15,9 +15,11 @@ limitations under the License.
 */
 
 import { SpanAttributes } from '@opentelemetry/api';
+import { SpanProcessor } from '@opentelemetry/sdk-trace-base';
 import { expect } from 'chai';
-import Rum from '../src';
+import Rum, { INSTRUMENTATIONS_ALL_DISABLED } from '../src';
 import { updateSessionStatus } from '../src/session';
+import { SpanCapturer } from './utils';
 
 describe('SplunkOtelWeb', () => {
   afterEach(() => {
@@ -146,4 +148,33 @@ describe('SplunkOtelWeb', () => {
       expect(Rum.inited).to.eq(false, 'Should be false after destroying.');
     });
   });
+
+  describe('addAction', () => {
+    let capturer: SpanCapturer;
+
+    beforeEach(() => {
+      Rum.init({
+        app: 'app-name',
+        beaconUrl: 'https://beacon',
+        rumAuth: '<token>',
+        instrumentations: INSTRUMENTATIONS_ALL_DISABLED,
+      });
+
+      capturer = new SpanCapturer();
+      Rum.provider?.addSpanProcessor(capturer as any as SpanProcessor);
+    });
+
+    it('should not crash when called without attributes', () => {
+      expect(() => Rum.addAction('test-action')).to.not.throw();
+      expect(capturer.spans).to.have.lengthOf(1);
+      expect(capturer.spans[0].name).to.eq('test-action');
+    });
+
+    it('should set attributes when provided', () => {
+      Rum.addAction('test-action', { key: 'value' });
+      expect(capturer.spans).to.have.lengthOf(1);
+      expect(capturer.spans[0].name).to.eq('test-action');
+      expect(capturer.spans[0].attributes).to.deep.include({ key: 'value' });
+    });
+  });
 });