Handle unhandled exception \ error \ panic

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How to catch unhandled exceptions that can occur in commands or somewhere else?

One option that ive found is returning Result in commands. It is good point, but what to do if some exceptions are unhandled in commands scope

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Panicking is a mechanism for crashing a thread in an orderly way. Unlike Result-based errors or exceptions in other languages, panics are not intended to be caught or handled.

By default, panicking terminates the current thread by unwinding the stack, executing all destructors as it goes. This means that the program can be left in a consistent state and the rest of the program can carry on executing.

You can also configure your program (by adding panic = 'abort' to the appropriate profile in your Cargo.toml) to abort on panic. In this case, the whole program exits immediately when a panic occurs. Using abort-on-panic will make your program slightly more performant (because stack unwinding doesn't need to be considered, similar to using C++ without exceptions). However, it can make your program less robust (a single thread cannot crash without crashing the whole program) and it means destructors won't be run on panic.

Even in the default unwind-on-panic configuration, causing a panic while the thread is already panicking will cause the whole program to abort. You must therefore be very careful that destructors cannot panic under any circumstance. You can check if the current thread is panicking by using the std::thread::panicking function.

When a panic occurs, a panic hook function is called. By default, this prints a message and possibly a backtrace to stderr, but it can be customised. See the docs for std::panic for more information. The panic hook is called whether the panic will unwind or abort.

In a no-std crate, you'll need to set your own panic handler. Use the #[panic_handler] attribute and see the docs for core::panicking for more info.

For more details on how panicking is implemented, see this blog post; for more on if and when you should panic (particularly using unwrap see this one.

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https://v2.tauri.app/develop/calling-rust/#error-handling