New materials don't even have an ID anymore

Handle that case as well.

Honestly the best solution would be to just get rid of getBlockIDAt as it's only used in two places where it could be trivially replaced

spigot/src/main/java/org/dynmap/bukkit/DynmapPlugin.java

@@ -183,12 +183,17 @@ public class DynmapPlugin extends JavaPlugin implements DynmapAPI {
             } catch (NoSuchMethodError e) {
                 // We failed once, no need to retry
                 tryNativeId.set(false);
+            } catch (java.lang.IllegalArgumentException e) {
+                // Ignore this entirely, as modern materials throw
+                // java.lang.IllegalArgumentException: Cannot get ID of Modern Material
             }
         }
 
         // We're living in a world where numerical IDs have been phased out completely.
-        // Let's return *some* number, because we need one
-        return material.ordinal();
+        // Let's return *some* number, because we need one.
+        // Also in that case we are adding a constant to ensure we're not conflicting with the
+        // actual IDs
+        return material.ordinal() + (1 << 20);
     }
     private static final int getBlockIdFromBlock(Block block) {
         return getBlockIdFromMaterial(block.getType());