loottrackerclient: log when submitting loot isn't successful

http-api/src/main/java/net/runelite/http/api/loottracker/LootTrackerClient.java

@@ -80,8 +80,15 @@ public class LootTrackerClient
 
 			@Override
 			public void onResponse(Call call, Response response)
+			{
+				if (response.isSuccessful())
 				{
 					log.debug("Submitted loot");
+				}
+				else
+				{
+					log.warn("Error submitting loot: {} - {}", response.code(), response.message());
+				}
 				response.close();
 				future.complete(null);
 			}