Unexpected end of plain scalar while parsing string

[Proximyst]

With the following document:

hello:
  world: this is a string
    --- still a string

and the reproduction code:

use saphyr::{LoadableYamlNode, Yaml};

fn main() {
    let documents = Yaml::load_from_str(include_str!("document.yaml"));
    println!("{:#?}", documents);
}

You get an error back:

Err(
    ScanError {
        mark: Marker {
            index: 37,
            line: 3,
            col: 4,
        },
        info: "unexpected end of plain scalar",
    },
)

Tools like yq parse this perfectly fine:

$ yq '.' src/document.yaml
hello:
  world: this is a string --- still a string