RaResponder: log instead of throw exception

Throwing an exception in RaResponder crashes the test process (as it
runs in a secondary thread). This is not very useful as that will fail
the execution of all the other tests.
Adding a log statement instead of throwing an exception makes more sense
as the tests will most likely fail anyways.

Test: atest EthernetManagerTest
Change-Id: I9c5f5dc417dad7df1c7f729caa4e0259ed71591f
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java b/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
index 21cb149..478161d 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
+++ b/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
@@ -35,6 +35,7 @@
 import android.net.LinkAddress;
 import android.net.MacAddress;
 import android.util.ArrayMap;
+import android.util.Log;
 import android.util.Pair;
 
 import com.android.net.module.util.Ipv6Utils;
@@ -130,7 +131,9 @@
         try {
             reader.sendResponse(buffer);
         } catch (IOException e) {
-            throw new RuntimeException("Failed to send buffer.");
+            // Throwing an exception here will crash the test process. Let's stick to logging, as
+            // the test will fail either way.
+            Log.e(TAG, "Failed to send buffer", e);
         }
     }