static <C, T extends Throwable> @NonNull ExceptionHandler<C, T> unwrappingHandler() {
        return unwrappingHandler(throwable -> true);
    }
Returns an exception handler that throws the cause of the {@link ExceptionContext#exception()} if it's
not {@code null}.
Otherwise, it will re-throw the {@link ExceptionContext#exception()}.

@param <C> the command sender type
@param <T> the exception type
@return the exception handler
cloud-core/src/main/java/org/incendo/cloud/exception/handling/ExceptionHandler.java