[CDM Bug] Fix a crash issue when serviceConnector is empty

serviceConnector is empty when there's no CompanionDeviceService
implementer declared or the permission is missing.

Fix: 219784113

Test: make
Change-Id: If6e3eed04323b520e409bc31dc3960e9dfc5d41a

services/companion/java/com/android/server/companion/CompanionApplicationController.java

@@ -26,6 +26,7 @@ import android.content.ComponentName;
 import android.content.Context;
 import android.os.Handler;
 import android.util.Log;
+import android.util.Slog;
 import android.util.SparseArray;
 
 import com.android.internal.annotations.GuardedBy;
@@ -120,6 +121,12 @@ class CompanionApplicationController {
             mBoundCompanionApplications.setValueForPackage(userId, packageName, serviceConnectors);
         }
 
+        if (serviceConnectors.isEmpty()) {
+            Slog.e(TAG, "Can't find CompanionDeviceService implementer in package: "
+                    + packageName + ". Please check if they are correctly declared.");
+            return;
+        }
+
         // The first connector in the list is always the primary connector: set a listener to it.
         serviceConnectors.get(0).setListener(this::onPrimaryServiceBindingDied);