fix(web): filter benign ResizeObserver loop warning from PostHog

packages/web/src/auth/posthog/posthog-exception-filter.util.test.ts

@@ -70,6 +70,30 @@ describe("filterPosthogBeforeSend", () => {
     ).toBeNull();
   });
 
+  it("drops the ResizeObserver loop completed browser warning", () => {
+    expect(
+      filterPosthogBeforeSend(
+        exceptionEvent([
+          {
+            type: "Error",
+            value:
+              "ResizeObserver loop completed with undelivered notifications.",
+          },
+        ]),
+      ),
+    ).toBeNull();
+  });
+
+  it("drops the Firefox ResizeObserver loop limit exceeded variant", () => {
+    expect(
+      filterPosthogBeforeSend(
+        exceptionEvent([
+          { type: "Error", value: "ResizeObserver loop limit exceeded" },
+        ]),
+      ),
+    ).toBeNull();
+  });
+
   it("keeps Script error. when stack frames are present", () => {
     const event = exceptionEvent([
       {

packages/web/src/auth/posthog/posthog-exception-filter.util.ts

@@ -16,6 +16,17 @@ const CEFSHARP_SCANNER_MESSAGE =
  */
 const SCRIPT_ERROR_MESSAGE = "Script error.";
 
+/**
+ * Benign browser warning fired via `window.onerror` when a ResizeObserver
+ * callback can't finish notifying within one frame (e.g. it triggers layout
+ * that would require another cycle). Chrome/Firefox surface it as a script
+ * error even though nothing threw; it's not actionable on its own.
+ */
+const RESIZE_OBSERVER_LOOP_MESSAGES = new Set([
+  "ResizeObserver loop completed with undelivered notifications.",
+  "ResizeObserver loop limit exceeded",
+]);
+
 type ExceptionEntry = {
   type?: unknown;
   value?: unknown;
@@ -61,6 +72,8 @@ const isDroppableException = (entry: ExceptionEntry): boolean => {
 
   if (entry.value === CEFSHARP_SCANNER_MESSAGE) return true;
 
+  if (RESIZE_OBSERVER_LOOP_MESSAGES.has(entry.value)) return true;
+
   // Opaque cross-origin errors. Keep the rare case where frames somehow
   // survived sanitization so a real stack is never discarded.
   if (entry.value === SCRIPT_ERROR_MESSAGE && !hasStackFrames(entry)) {