Abort boot when MB_STATIC_BUILDINGS is missing or unknown

A missing setting threw a NullPointerException, and an unknown one fell
back to DB without a word. Both now abort with a message, as
MB_STATIC_RUNEGATES does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/engine/mbEnums.java

@@ -3120,6 +3120,7 @@ public class mbEnums {
 
     // MB_STATIC_BUILDINGS (World Boot Plan 2.4). DB: static buildings from obj_building, before the migration.
     // PARITY: DB load plus the JSON buildings compared and the migration mapping written. JSON: after the migration.
+    // Required; null when missing or unknown, and boot aborts.
     public enum StaticBuildingMode {
         DB,
         PARITY,
@@ -3127,11 +3128,14 @@ public class mbEnums {
 
         public static StaticBuildingMode fromConfig(String configValue) {
 
+            if (configValue == null)
+                return null;
+
             for (StaticBuildingMode mode : values())
                 if (mode.name().equalsIgnoreCase(configValue.trim()))
                     return mode;
 
-            return DB;
+            return null;
         }
     }
 

src/engine/server/world/WorldServer.java

@@ -557,6 +557,12 @@ public class WorldServer {
         long start = System.currentTimeMillis();
 
         staticBuildingMode = StaticBuildingLoader.getMode();
+
+        if (staticBuildingMode == null) {
+            Logger.error("ABORT! MB_STATIC_BUILDINGS is '" + ConfigManager.MB_STATIC_BUILDINGS.getValue() + "'; set it to DB, PARITY or JSON.");
+            exitServer(1);
+        }
+
         staticZoneRows = DbManager.StaticWorldQueries.COUNT_STATIC_ZONE_ROWS();
         Logger.info("Static buildings: MB_STATIC_BUILDINGS " + staticBuildingMode + ", " + staticZoneRows + " static zone rows in obj_zone");