Addressed comments by yunhanw-google related to error checking and logging and also fixed a tv-casting-app connection bug (#33010)

Author: pgregorr-amazon

examples/tv-casting-app/android/App/app/src/main/java/com/matter/casting/DiscoveryExampleFragment.java

@@ -216,7 +216,6 @@ public void onResume() {
   public void onPause() {
     super.onPause();
     Log.i(TAG, "onPause() called");
-    stopDiscovery();
   }
 
   /** Interface for notifying the host. */

examples/tv-casting-app/android/App/app/src/main/jni/cpp/core/CastingPlayerDiscovery-JNI.cpp

@@ -246,7 +246,7 @@ JNI_METHOD(jobject, removeCastingPlayerChangeListener)(JNIEnv * env, jobject, jo
 
         return support::convertMatterErrorFromCppToJava(CHIP_NO_ERROR);
     }
-    else if (DiscoveryDelegateImpl::GetInstance()->castingPlayerChangeListenerJavaObject.ObjectRef() == nullptr)
+    else if (!DiscoveryDelegateImpl::GetInstance()->castingPlayerChangeListenerJavaObject.HasValidObjectRef())
     {
         ChipLogError(
             AppServer,

src/platform/android/DnssdImpl.cpp

@@ -191,6 +191,8 @@ CHIP_ERROR ChipDnssdBrowse(const char * type, DnssdServiceProtocol protocol, Ine
 
     std::string serviceType = GetFullTypeWithSubTypes(type, protocol);
     JNIEnv * env            = JniReferences::GetInstance().GetEnvForCurrentThread();
+    VerifyOrReturnError(env != nullptr, CHIP_JNI_ERROR_NO_ENV,
+                        ChipLogError(Discovery, "Failed to GetEnvForCurrentThread for ChipDnssdBrowse"));
     UtfString jniServiceType(env, serviceType.c_str());
 
     env->CallVoidMethod(sBrowserObject.ObjectRef(), sBrowseMethod, jniServiceType.jniValue(), reinterpret_cast<jlong>(callback),
@@ -204,22 +206,29 @@ CHIP_ERROR ChipDnssdBrowse(const char * type, DnssdServiceProtocol protocol, Ine
         return CHIP_JNI_ERROR_EXCEPTION_THROWN;
     }
 
-    auto sdCtx        = chip::Platform::New<BrowseContext>(callback);
+    auto sdCtx = chip::Platform::New<BrowseContext>(callback);
+    VerifyOrReturnError(nullptr != sdCtx, CHIP_ERROR_NO_MEMORY,
+                        ChipLogError(Discovery, "Failed allocate memory for BrowseContext in ChipDnssdBrowse"));
     *browseIdentifier = reinterpret_cast<intptr_t>(sdCtx);
 
     return CHIP_NO_ERROR;
 }
 
 CHIP_ERROR ChipDnssdStopBrowse(intptr_t browseIdentifier)
 {
+    VerifyOrReturnError(browseIdentifier != 0, CHIP_ERROR_INVALID_ARGUMENT,
+                        ChipLogError(Discovery, "ChipDnssdStopBrowse Invalid argument browseIdentifier = 0"));
     VerifyOrReturnError(sBrowserObject.HasValidObjectRef() && sStopBrowseMethod != nullptr, CHIP_ERROR_INVALID_ARGUMENT);
 
     JNIEnv * env = JniReferences::GetInstance().GetEnvForCurrentThread();
-    auto ctx     = reinterpret_cast<BrowseContext *>(browseIdentifier);
+    VerifyOrReturnError(env != nullptr, CHIP_JNI_ERROR_NO_ENV,
+                        ChipLogError(Discovery, "Failed to GetEnvForCurrentThread for ChipDnssdStopBrowse"));
+    auto ctx = reinterpret_cast<BrowseContext *>(browseIdentifier);
 
     env->CallVoidMethod(sBrowserObject.ObjectRef(), sStopBrowseMethod, reinterpret_cast<jlong>(ctx->callback));
 
     chip::Platform::Delete(ctx);
+    ctx = nullptr;
     if (env->ExceptionCheck())
     {
         ChipLogError(Discovery, "Java exception in ChipDnssdStopBrowse");
@@ -339,6 +348,12 @@ void InitializeWithObjects(jobject resolverObject, jobject browserObject, jobjec
         env->ExceptionClear();
     }
 
+    if (sStopBrowseMethod == nullptr)
+    {
+        ChipLogError(Discovery, "Failed to access Discover 'stopDiscover' method");
+        env->ExceptionClear();
+    }
+
     if (sGetTextEntryKeysMethod == nullptr)
     {
         ChipLogError(Discovery, "Failed to access MdnsCallback 'getTextEntryKeys' method");