From 044d71258081f1f3b370c860d3d02cd7da7aeaf9 Mon Sep 17 00:00:00 2001
From: Ben Senescu <44480372+bensenescu@users.noreply.github.com>
Date: Wed, 26 Aug 2026 09:33:43 -0400
Subject: [PATCH] Ignore TanStack Query CancelledError in client error tracking
 (#524)

---
 src/client/lib/posthog.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/client/lib/posthog.ts b/src/client/lib/posthog.ts
index 2acff78..5298361 100644
--- a/src/client/lib/posthog.ts
+++ b/src/client/lib/posthog.ts
@@ -20,12 +20,16 @@ type ExceptionEntry = {
   stacktrace?: { frames?: unknown[] };
 };
 
-// Unactionable exceptions we don't want polluting error tracking. They share
+// Unactionable exceptions we don't want polluting error tracking. Most share
 // the trait of not being our code: browser extensions inject promise rejections
 // and cross-origin scripts surface as a detail-less "Script error.", while the
 // global onerror handler synthesizes a stackless "undefined" when it fires
 // without a real Error object. Real app errors always carry a stack, so the
 // "undefined" rule is gated on synthetic + no frames to avoid false drops.
+// The rest are expected cancellations: TanStack Query throws "CancelledError"
+// when a route load is abandoned mid-flight (navigating away), which is normal
+// behavior, not a failure. Matched exactly so a real error that merely mentions
+// cancellation still gets captured.
 function isIgnorableException(
   properties: Record<string, unknown> | undefined,
 ): boolean {
@@ -36,6 +40,7 @@ function isIgnorableException(
     if (value.includes("Object Not Found Matching Id")) return true;
     if (value === "Script error.") return true;
     if (value.includes("signal is aborted without reason")) return true;
+    if (value === "CancelledError") return true;
     const frames = entry?.stacktrace?.frames;
     return (
       value === "undefined" &&