Carriage: pos / length accessors: fix uninitialized value warnings

	$ref->{start_meters} = $pos->{start};

	$ref->{end_meters}   = $pos->{end};

	if (    defined $pos->{start}

		and defined $platform->{start}

		and $platform_length )

	{

		$ref->{start_percent}

		  = ( $pos->{start} - $platform->{start} ) * 100 / $platform_length;

	}

	if (    defined $pos->{end}

		and defined $platform->{start}

		and $platform_length )

	{

		$ref->{end_percent}

		  = ( $pos->{end} - $platform->{start} ) * 100 / $platform_length;

	if ( defined $pos->{start} and defined $pos->{end} ) {

		$ref->{length_meters} = $pos->{start} - $pos->{end};

	}

	$ref->{length_percent} = $ref->{end_percent} - $ref->{start_percent};

	if (   $pos->{start} eq ''

	if (   not defined $pos->{start}

		or not defined $pos->{end}

		or $pos->{start} eq ''

		or $pos->{end} eq '' )

	{

		$ref->{position}{valid} = 0;

	}

	else {

		$ref->{position}{valid} = 1;

		$ref->{length_meters} = $pos->{start} - $pos->{end};

	}

	if ( defined $ref->{start_percent} and defined $ref->{end_percent} ) {

		$ref->{length_percent} = $ref->{end_percent} - $ref->{start_percent};

	}

	return $self;