chore: upadte event_library and add todos

pkg/event/event_library.go

@@ -1,14 +1,27 @@
 package event
 
+import "fmt"
+
+// TODO: Define our events properly. These are placeholders and should be replaced with actual event definitions.
+
 func (a *EventTracker) TrackUserLogin(userID string, client *EventClient) error {
+	if a == nil {
+		return fmt.Errorf("EventTracker is nil")
+	}
 	return a.TrackAndSendEvent("user_login", map[string]interface{}{"user_id": userID}, client)
 }
 
 func (a *EventTracker) TrackPageView(pageURL string, client *EventClient) error {
+	if a == nil {
+		return fmt.Errorf("EventTracker is nil")
+	}
 	return a.TrackAndSendEvent("page_view", map[string]interface{}{"url": pageURL}, client)
 }
 
 func (a *EventTracker) TrackPurchase(productID string, amount float64, client *EventClient) error {
+	if a == nil {
+		return fmt.Errorf("EventTracker is nil")
+	}
 	return a.TrackAndSendEvent("purchase", map[string]interface{}{
 		"product_id": productID,
 		"amount":     amount,