diff --git a/openc3-cosmos-init/plugins/packages/openc3-js-common/src/services/cable.js b/openc3-cosmos-init/plugins/packages/openc3-js-common/src/services/cable.js
index fc1ec780f7..4899bfb955 100644
--- a/openc3-cosmos-init/plugins/packages/openc3-js-common/src/services/cable.js
+++ b/openc3-cosmos-init/plugins/packages/openc3-js-common/src/services/cable.js
@@ -63,11 +63,24 @@ class ResilientSubscription {
     return this._subscription?.identifier
   }
 
+  // Once the owner has torn this subscription down (unsubscribe, or
+  // Cable#disconnect when its component unmounts) there's nothing to perform
+  // on. Callers perform from async callbacks, e.g. after the token refresh in
+  // a connected handler, that can land after the teardown, and anycable
+  // rejects those on the closed consumer with NoConnectionError. Nobody awaits
+  // them, so that surfaced as an unhandled rejection - e.g. a Telemetry Viewer
+  // screen closed right after it opened.
   perform(action, data) {
+    if (this._unsubscribed) {
+      return Promise.resolve()
+    }
     return this._subscription?.perform(action, data)
   }
 
   send(data) {
+    if (this._unsubscribed) {
+      return Promise.resolve()
+    }
     return this._subscription?.send(data)
   }
 
diff --git a/playwright/tests/fixture.ts b/playwright/tests/fixture.ts
index ff207f7b33..2636eb321d 100644
--- a/playwright/tests/fixture.ts
+++ b/playwright/tests/fixture.ts
@@ -34,6 +34,10 @@ const startCoverage = async (page: any) => {
 const stopCoverage = async (page: any) => {
   try {
     const coverage = await page.coverage.stopJSCoverage()
+    // Empty when the page never loaded a script with a URL (e.g. a blank popup)
+    // or profiling never started on it. MCR rejects [] with "The added coverage
+    // data must be Array(V8) or Object(Istanbul)", so skip it.
+    if (!coverage.length) return
     // Appends raw V8 data to coverage/.cache (safe across workers AND
     // separate `playwright test` invocations); generate-coverage.mjs
     // merges everything into one report at the end of `pnpm test`