31 code refactoring

[g0dm0d]

1. Added errors from the rust side for easier error output.

#[tauri::command]
fn my_custom_command() -> Result<String, String> {
  // If something fails
  Err("This failed!".into())
  // If it worked
  Ok("This worked!".into())
}

invoke('my_custom_command')
  .then((message) => console.log(message))
  .catch((error) => console.error(error))

2. Migration of users from toml to json. Because it is more convenient.

[
  {
    "uuid": "000",
    "username": "STEVE",
    "refresh_token": "secret",
    "access_token": "secret",
    "access_exp": 1696633450,
    "minecraft_token": "secret",
    "minecraft_exp": 1696633450
  }
]