# Objective
Currently, `bevy_dynamic_plugin` simply panics on error. This makes it impossible to handle failures in applications that use this feature.
For example, I'd like to build an optional expansion for my game, that may not be distributed to all users. I want to use `bevy_dynamic_plugin` for loading it. I want my game to try to load it on startup, but continue without it if it cannot be loaded.
## Solution
- Make the `dynamically_load_plugin` function return a `Result`, so it can gracefully return loading errors.
- Create an error enum type, to provide useful information about the kind of error. This adds `thiserror` to the dependencies of `bevy_dynamic_plugin`, but that dependency is already used in other parts of bevy (such as `bevy_asset`), so not a big deal.
I chose not to change the behavior of the builder method in the App extension trait. I kept it as panicking. There is no clean way (that I'm aware of) to make a builder-style API that has fallible methods. So it is either a panic or a warning. I feel the panic is more appropriate.
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## Changelog
### Changed
- `bevy_dynamic_plugin::dynamically_load_plugin` now returns `Result` instead of panicking, to allow for error handling
Objective
During work on #3009 I've found that not all jobs use actions-rs, and therefore, an previous version of Rust is used for them. So while compilation and other stuff can pass, checking markup and Android build may fail with compilation errors.
Solution
This PR adds `action-rs` for any job running cargo, and updates the edition to 2021.
This relicenses Bevy under the dual MIT or Apache-2.0 license. For rationale, see #2373.
* Changes the LICENSE file to describe the dual license. Moved the MIT license to docs/LICENSE-MIT. Added the Apache-2.0 license to docs/LICENSE-APACHE. I opted for this approach over dumping both license files at the root (the more common approach) for a number of reasons:
* Github links to the "first" license file (LICENSE-APACHE) in its license links (you can see this in the wgpu and rust-analyzer repos). People clicking these links might erroneously think that the apache license is the only option. Rust and Amethyst both use COPYRIGHT or COPYING files to solve this problem, but this creates more file noise (if you do everything at the root) and the naming feels way less intuitive.
* People have a reflex to look for a LICENSE file. By providing a single license file at the root, we make it easy for them to understand our licensing approach.
* I like keeping the root clean and noise free
* There is precedent for putting the apache and mit license text in sub folders (amethyst)
* Removed the `Copyright (c) 2020 Carter Anderson` copyright notice from the MIT license. I don't care about this attribution, it might make license compliance more difficult in some cases, and it didn't properly attribute other contributors. We shoudn't replace it with something like "Copyright (c) 2021 Bevy Contributors" because "Bevy Contributors" is not a legal entity. Instead, we just won't include the copyright line (which has precedent ... Rust also uses this approach).
* Updates crates to use the new "MIT OR Apache-2.0" license value
* Removes the old legion-transform license file from bevy_transform. bevy_transform has been its own, fully custom implementation for a long time and that license no longer applies.
* Added a License section to the main readme
* Updated our Bevy Plugin licensing guidelines.
As a follow-up we should update the website to properly describe the new license.
Closes#2373
