fix(stealth): address Copilot review findings [CL-2]

- Guard err.stack in generateErrorObject before cleanErrorStack/splitStack
- Fix propertyCollection guard to check .length instead of comparing object to string
- Fix typos: Depcrecated→Deprecated, AudioContenxt→AudioContext
- Remove stale TODO comment in iframe contentWindow instrumentation

Author: vringar

Extension/src/stealth/error.ts

@@ -5,6 +5,7 @@ function generateErrorObject(
   err: { stack: any; name: string | number; message: any },
   context = undefined,
 ) {
+  if (!err || typeof err.stack !== "string") return err;
   context = context !== undefined ? context : window;
   const cleaned = cleanErrorStack(err.stack);
   const stack = splitStack(cleaned);

Extension/src/stealth/instrument.ts

@@ -854,7 +854,7 @@ function startInstrument(context) {
       continue;
     }
     // Instrument each Property per object/prototype
-    if (propertyCollection[0] !== "") {
+    if (propertyCollection.length > 0) {
       propertyCollection.forEach(({ depth, propertyNames, object }) => {
         if (needsWrapper(object)) {
           propertyNames.forEach((propertyName) =>

Extension/src/stealth/settings.ts

@@ -2,7 +2,7 @@ import { JSInstrumentSettings } from "../types/js_instrument_settings";
 
 export const jsInstrumentationSettings: JSInstrumentSettings = [
   {
-    object: "ScriptProcessorNode", // Depcrecated. Replaced by AudioWorkletNode
+    object: "ScriptProcessorNode", // Deprecated. Replaced by AudioWorkletNode
     instrumentedName: "ScriptProcessorNode",
     depth: 0,
     logSettings: {
@@ -146,10 +146,10 @@ export const jsInstrumentationSettings: JSInstrumentSettings = [
     },
   },
 
-  // Add shared prototype by AudioContenxt/OfflineAudioContext
+  // Add shared prototype by AudioContext/OfflineAudioContext
   {
     object: "AudioContext",
-    instrumentedName: "[AudioContenxt|OfflineAudioContext]",
+    instrumentedName: "[AudioContext|OfflineAudioContext]",
     depth: 1,
     logSettings: {
       propertiesToInstrument: [],

Extension/src/stealth/stealth.ts

@@ -164,7 +164,6 @@ function protectFrameProperties({
       constructor.prototype,
       "contentWindow",
     );
-    // TODO: Continue here!!!!
     const originalContentWindowGetter = contentWindowDescriptor.get;
     const contentWindowTemp = {
       get contentWindow() {