# Objective

- Silence `Failed to send DropEvent for StrongHandle "SendError(..)"`
errors when `StrongHandle` were dropped during application shutdown.
- Re-export `BoxedFuture` considering that it's used everywhere in
bevy_asset
- Fixed an issue introduced by bevyengine#9729. 
  ```
Asset 'final_gather.rgen' encountered an error in
dust_render::shader::spirv::SpirvLoader: Failed to deserialize asset
meta: SpannedError { code: InvalidValueForType { expected: "string
AssetPath", found: "a sequence" }, position: Position { line: 9, col: 24
} }
  ```
Basically, for processed assets with dependencies, bevy will serialize
the metafile as follows:
  ```
  (
    meta_format_version: "1.0",
    processed_info: Some((
hash: (203, 239, 108, 156, 180, 23, 157, 217, 159, 36, 158, 193, 185,
253, 242, 156),
full_hash: (77, 58, 30, 200, 21, 180, 221, 133, 151, 83, 247, 47, 193,
70, 228, 97),
        process_dependencies: [
            (
full_hash: (56, 46, 55, 118, 3, 6, 213, 250, 124, 26, 153, 87, 15, 85,
4, 89),
                path: ("standard.glsl"), # <<---------- See here
            ),
        ],
    )),
    asset: Load(
        loader: "dust_render::shader::spirv::SpirvLoader",
        settings: (),
    ),
  )
  ```
`AssetPath` gets serialized as `("standard.glsl")` which was then
deserialized as a sequence instead of our `AssetPath`.

## Solution

- Serialize `AssetPath` directly as a string instead. The above metafile
would be serialized as follows:
 ```
  (
    meta_format_version: "1.0",
    processed_info: Some((
hash: (203, 239, 108, 156, 180, 23, 157, 217, 159, 36, 158, 193, 185,
253, 242, 156),
full_hash: (77, 58, 30, 200, 21, 180, 221, 133, 151, 83, 247, 47, 193,
70, 228, 97),
        process_dependencies: [
            (
full_hash: (56, 46, 55, 118, 3, 6, 213, 250, 124, 26, 153, 87, 15, 85,
4, 89),
path: "standard.glsl", # <<------- No longer a tuple struct
            ),
        ],
    )),
    asset: Load(
        loader: "dust_render::shader::spirv::SpirvLoader",
        settings: (),
    ),
  )
  ```

---