A write with if_exists: :error found a file already there. Read that file and decide again.
iex> disk = Fil.disk(adapter: Fil.Adapter.Memory)
iex> Fil.write!(disk, "once.txt", "first")
iex> {:error, %Fil.AlreadyExistsError{}} = Fil.write(disk, "once.txt", "second", if_exists: :error)
Summary
Types
@type t() :: %Fil.AlreadyExistsError{ __exception__: term(), disk: Fil.Disk.t() | nil, op: Fil.Op.name() | nil, path: String.t() | nil, reason: term() }