Function validation_diagnostics 

pub(crate) fn validation_diagnostics(
    fs: &FileSystem,
    errors: &[ValidationError],
) -> BTreeMap<PathBuf, Vec<Diagnostic>>

Convert ValidationErrors into LSP diagnostics grouped by file path.

When an error carries a byte_offset, the file is read and a Rope is built so the offset can be converted to a precise line/column position. Errors without an offset (file-level) fall back to (0, 0).

Returns an empty map when errors is empty.