From d05a9d400060ae2f9b4ff9a2faee3a0f2ad74e6d Mon Sep 17 00:00:00 2001
From: Alex Vandiver <alexmv@zulip.com>
Date: Tue, 18 Jul 2023 18:01:27 +0000
Subject: [PATCH] reactions: Do not send server error reports for duplicate
 requests.

---
 web/src/reactions.js        | 11 +++++++++--
 web/tests/reactions.test.js |  2 +-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/web/src/reactions.js b/web/src/reactions.js
index a6d2637947..e3402949e4 100644
--- a/web/src/reactions.js
+++ b/web/src/reactions.js
@@ -85,8 +85,15 @@ function update_ui_and_send_reaction_ajax(message_id, reaction_info) {
         },
         error(xhr) {
             view.waiting_for_server_request_ids.delete(reaction_request_id);
-            const response = channel.xhr_error_message("Error sending reaction", xhr);
-            blueslip.error(response);
+            if (
+                xhr.responseJSON?.code === "REACTION_ALREADY_EXISTS" ||
+                xhr.responseJSON?.code === "REACTION_DOES_NOT_EXIST"
+            ) {
+                // Don't send error report for simple precondition failures caused by race
+                // conditions; the user already got what they wanted
+            } else {
+                blueslip.error(channel.xhr_error_message("Error sending reaction", xhr));
+            }
         },
     };
 
diff --git a/web/tests/reactions.test.js b/web/tests/reactions.test.js
index 09ccfbe6ac..1ebc54ae22 100644
--- a/web/tests/reactions.test.js
+++ b/web/tests/reactions.test.js
@@ -268,7 +268,7 @@ test("sending", ({override, override_rewire}) => {
         // Since this path calls blueslip.warn, we need to handle it.
         blueslip.expect("error", "XHR error message.");
         channel.xhr_error_message = () => "XHR error message.";
-        args.error();
+        args.error({responseJSON: {msg: "Some error message"}});
     }
     emoji_name = "alien"; // not set yet
     {