fix a memory leak and most warnings

src/block_placement.rs

@@ -1,4 +1,3 @@
-use glam::Vec3;
 use shipyard::{UniqueViewMut, UniqueView, View, IntoIter};
 use crate::{
   player::MainPlayer, 

src/rendering/selection_box.rs

@@ -51,7 +51,6 @@ pub fn render_selection_box(
   lookat: View<LookingAtBlock>,
   camera: View<Camera>,
   mut target: NonSendSync<UniqueViewMut<RenderTarget>>, 
-  display: NonSendSync<UniqueView<Renderer>>,
   program: NonSendSync<UniqueView<SelBoxShaderPrefab>>,
   buffers: NonSendSync<UniqueView<SelectionBoxBuffers>>,
 ) {

src/world.rs

@@ -85,6 +85,7 @@ impl ChunkMeshStorage {
   }
   pub fn insert(&mut self, mesh: ChunkMesh) -> usize {
     let index = self.index;
+    debug_assert!(self.meshes.get(&index).is_none());
     self.meshes.insert_unique_unchecked(index, mesh);
     self.index += 1;
     index

src/world/loading.rs

@@ -210,11 +210,16 @@ fn process_completed_tasks(
           //apply the mesh
           let vertex_buffer = VertexBuffer::new(&renderer.display, &vertices).unwrap();
           let index_buffer = IndexBuffer::new(&renderer.display, PrimitiveType::TrianglesList, &indexes).unwrap();
-          let mesh_index = meshes.insert(ChunkMesh {
+          let mesh = ChunkMesh {
             vertex_buffer,
             index_buffer,
-          });
-          chunk.mesh_index = Some(mesh_index);
+          };
+          if let Some(index) = chunk.mesh_index {
+            meshes.update(index, mesh).expect("Mesh update failed");
+          } else {
+            let mesh_index = meshes.insert(mesh);
+            chunk.mesh_index = Some(mesh_index);
+          }
 
           //update chunk state
           chunk.current_state = CurrentChunkState::Rendered;