Fix two null issues

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

@@ -766,7 +766,7 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
         final PendingMicrosoftAuthentication.AuthenticationTask task = geyser.getPendingMicrosoftAuthentication().getOrCreateTask(
                 getAuthData().xuid()
         );
-        if (task.getAuthentication().isDone()) {
+        if (task.getAuthentication() != null && task.getAuthentication().isDone()) {
             onMicrosoftLoginComplete(task);
         } else {
             task.resetRunningFlow();

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

@@ -105,6 +105,10 @@ public class PendingMicrosoftAuthentication {
         }
 
         public void resetRunningFlow() {
+            if (authentication == null) {
+                return;
+            }
+
             // Interrupt the current flow
             this.authentication.cancel(true);
         }