diff --git a/src/services/NotificationService.ts b/src/services/NotificationService.ts
index 1a66870..1c16c84 100644
--- a/src/services/NotificationService.ts
+++ b/src/services/NotificationService.ts
@@ -72,23 +72,28 @@ export class NotificationService {
     return this._lastRefreshedTimeMs && Date.now() - this._lastRefreshedTimeMs < thirtyMinutesMs;
   }
 
-  private async sendEtaNotificationImmediately({ deviceId, shuttleId, stopId }: ScheduledNotificationData): Promise<boolean> {
+  private async sendEtaNotificationImmediately(notificationData: ScheduledNotificationData): Promise<boolean> {
+    const { deviceId, shuttleId, stopId } = notificationData;
     this.reloadAPNsTokenIfTimePassed();
     const url = NotificationService.getAPNsFullUrlToUse(deviceId);
 
     const shuttle = await this.repository.getShuttleById(shuttleId);
     const stop = await this.repository.getStopById(stopId);
     const eta = await this.repository.getEtaForShuttleAndStopId(shuttleId, stopId);
-    // TODO: add more specific errors
     if (!shuttle) {
-      throw new Error("The shuttle given by the provided shuttleID doesn't exist.");
+      console.warn(`Notification ${notificationData} fell through; no associated shuttle`);
+      return false;
     }
     if (!stop) {
-      throw new Error("The shuttle given by the provided stopId doesn't exist.");
+      console.warn(`Notification ${notificationData} fell through; no associated stop`);
+      return false;
     }
-    // TODO: account for cases where ETA may not exist due to "data race" with ApiBasedRepositoryLoader
+
+    // Notification may not be sent if ETA is unavailable at the moment;
+    // this is fine because it will be sent again when ETA becomes available
     if (!eta) {
-      throw new Error("There is no ETA for this shuttle/stop.");
+      console.warn(`Notification ${notificationData} fell through; no associated ETA`);
+      return false;
     }
 
     // Send the fetch request