fixes ranges of perimeterinfo. fixes #1207

src/main/java/carpet/utils/PerimeterDiagnostics.java

@@ -89,6 +89,8 @@ public class PerimeterDiagnostics
         PerimeterDiagnostics diagnostic = new PerimeterDiagnostics(worldserver,ctype,el);
         EntityType type = EntityType.ZOMBIE;
         if (el != null) type = el.getType();
+        int minY = worldserver.getBottomY();
+        int maxY = worldserver.getTopY();
         for (int x = -128; x <= 128; ++x)
         {
             for (int z = -128; z <= 128; ++z)
@@ -97,7 +99,7 @@ public class PerimeterDiagnostics
                 {
                     continue;
                 }
-                for (int y= 0; y < 256; ++y)
+                for (int y= minY; y < maxY; ++y)
                 {
                     if ((Math.abs(y-eY)>128) )
                     {