Add measurements, improve MSL insert.

app/src/main/java/org/thoughtcrime/securesms/crypto/storage/TextSecureSessionStore.java

@@ -17,6 +17,7 @@ import org.whispersystems.libsignal.state.SessionRecord;
 import org.whispersystems.signalservice.api.SignalServiceSessionStore;
 
 import java.util.List;
+import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -57,6 +58,10 @@ public class TextSecureSessionStore implements SignalServiceSessionStore {
         throw new NoSessionException(message);
       }
 
+      if (sessionRecords.stream().anyMatch(Objects::isNull)) {
+        throw new NoSessionException("Failed to find at least one session.");
+      }
+
       return sessionRecords;
     }
   }