After fixing the argument issue, i found that the tree generation didn't work properly. In order to generate a tree, we need to spawn it from a block of air, on top a valid block. I reworked the entire brush to handle a safe generation with the arrow, and a forced generation with the gunpowder. The safe generation lets Minecraft decide if the terrain is valid to spawn a tree. The forced one tries to create the conditions needed to generate, with some limitations.
Bugfix for issue #23
After fixing the argument issue, i found that the tree generation didn't work properly. In order to generate a tree, we need to spawn it from a block of air, on top a valid block. I reworked the entire brush to handle a safe generation with the arrow, and a forced generation with the gunpowder. The safe generation lets Minecraft decide if the terrain is valid to spawn a tree. The forced one tries to create the conditions needed to generate, with some limitations.