From dbcc567a8fea9b5ef07fcad588e8268f3a23f9d4 Mon Sep 17 00:00:00 2001
From: Trevor Gerhardt <trevorgerhardt@gmail.com>
Date: Tue, 30 May 2023 16:46:06 +0800
Subject: [PATCH] Fix an NPE when task does not exist (#880)

Handle the case when `taskScheduler.getTaskForUser` returns `null` so that we to prevent `NullPointerException`s.
---
 .../conveyal/analysis/controllers/UserActivityController.java | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/main/java/com/conveyal/analysis/controllers/UserActivityController.java b/src/main/java/com/conveyal/analysis/controllers/UserActivityController.java
index c2beffd30..83b6f5389 100644
--- a/src/main/java/com/conveyal/analysis/controllers/UserActivityController.java
+++ b/src/main/java/com/conveyal/analysis/controllers/UserActivityController.java
@@ -58,6 +58,10 @@ private Object removeActivity (Request req, Response res) {
         UserPermissions userPermissions = UserPermissions.from(req);
         String id = req.params("id");
         Task task = taskScheduler.getTaskForUser(userPermissions.email, id);
+        // Check if task still exists before attempting to remove.
+        if (task == null) {
+            throw  AnalysisServerException.notFound("Task does not exist. It may have already been removed by another user.");
+        }
         // Disallow removing active tasks via the API.
         if (task.state.equals(Task.State.ACTIVE)) {
             throw AnalysisServerException.badRequest("Cannot clear an active task.");