Fix: protocol being null during online mode login (#4369)

* fix: protocol being null during online mode login

* gimme more space

* add debug logging for too early downstream packet sending

core/src/main/java/org/geysermc/geyser/session/GeyserSession.java

@@ -1633,6 +1633,15 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
      * @param intendedState the state the client should be in
      */
     public void sendDownstreamPacket(Packet packet, ProtocolState intendedState) {
+        // protocol can be null when we're not yet logged in (online auth)
+        if (protocol == null) {
+            if (geyser.getConfig().isDebugMode()) {
+                geyser.getLogger().debug("Tried to send downstream packet with no downstream session!");
+                Thread.dumpStack();
+            }
+            return;
+        }
+
         if (protocol.getState() != intendedState) {
             geyser.getLogger().debug("Tried to send " + packet.getClass().getSimpleName() + " packet while not in " + intendedState.name() + " state");
             return;