Error codes

#[error_code]
pub enum ErrorCode {
    #[msg("Invalid authority")]
    InvalidAuthority,
    #[msg("Insufficient funds")]
    InsufficientFunds,
    #[msg("Value exceeds maximum")]
    ValueTooLarge,
}

pub fn update(ctx: Context<Update>) -> Result<()> {
    require!(
        ctx.accounts.data.authority == ctx.accounts.user.key(),
        ErrorCode::InvalidAuthority
    );
    Ok(())
}