Fix another NPE

Author: eclipseisoffline

core/src/main/java/org/geysermc/geyser/session/cache/AdvancementsCache.java

@@ -76,7 +76,7 @@ public void setCurrentAdvancementCategoryId(String categoryId) {
             // Only open and show list form if we're going to a different category
             currentAdvancementCategoryId = categoryId;
             if (formOpen) {
-                buildAndShowListForm();
+                buildAndShowForm();
             }
         }
     }