Optionaloptions: SerialSessionOptionsSerialError when option values are out of range: SerialErrorCode.INVALID_CONNECTION_OPTIONS, SerialErrorCode.INVALID_FILTER_OPTIONS, SerialErrorCode.INVALID_TERMINAL_BUFFER_OPTIONS, or SerialErrorCode.INVALID_LINE_BUFFER_OPTIONS.
Merge and validate SerialSessionOptions into a fully resolved options object for internal session use.
Defaults and validation for nested buffers live next to their option types (resolveTerminalBufferOptions, resolveLineBufferOptions). This function is the single entry point that assembles connection + feature options for a session.